Liquid droplet ejecting method, liquid droplet ejection apparatus, inkjet recording apparatus, production method of fine particles, fine particle production apparatus, and toner

ABSTRACT

A liquid droplet ejecting method for ejecting a liquid from at least one ejection hole to form the liquid into liquid droplets, the method including:
         applying a vibration to the liquid in a liquid column resonance-generating liquid chamber, in which the ejection hole is formed, to form a standing wave through liquid column resonance, and   ejecting the liquid from the ejection hole, which is formed in a region corresponding to an antinode of the standing wave, to form the liquid into liquid droplets.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. application Ser. No.13/635,747, filed Sep. 18, 2012, allowed, which is a 371 ofPCT/JP11/57075, filed Mar. 16, 2011. The present application also claimspriority to Japanese patent applications JP2010-063302, filed Mar. 18,2010; JP2010-063089, filed Mar. 18, 2010; and JP2010-250765, filed Nov.9, 2010.

TECHNICAL FIELD

The present invention relates to a liquid droplet ejecting method, aliquid droplet ejection apparatus, and an inkjet recording apparatus.The present invention also relates to a method for producing fineparticles having uniform particle diameters by a spray granulationmethod, and a fine particle production apparatus. Further, the presentinvention relates to a toner produced by the production method of fineparticles or the fine particle production apparatus.

BACKGROUND ART

Firstly, background art relating to an inkjet recording apparatus usinga liquid droplet ejecting method, and a liquid droplet ejectionapparatus will be described below.

Inkjet recording apparatuses in current use are allowed to undergodisplacement of a piezoelectric element etc. provided in a liquidchamber in an ink head to eject an ink in the liquid chamber from inknozzles, in the form of ink droplets, and to adhere onto recordingpaper, thereby enabling printing on the recording paper. Such inkjetrecording apparatuses are widely prevalent because of their cheap costsand compactness. Most of the inkjet recording apparatuses use Helmholtzresonance vibration to eject liquid droplets, as described in PTL 1. Inan inkjet head using the Helmholtz resonance vibration, Helmholtzresonance vibration is excited, by a piezoelectric body, in a pressuregeneration chamber constituting the head so as to eject liquid dropletsfrom ejection holes. It is known that a resonance frequency of Helmholtzresonance vibration is set in view of a fluid compliance attributable tothe compressibility of an ink in a pressure generation chamber, arigidity compliance of materials themselves for an elastic plate and anejection hole plate each forming the pressure generation chamber, andinertance in opening of ejection holes and an ink supply port. Aresonance frequency f of Helmholtz resonance vibration in the pressuregeneration chamber is represented by the following Equation 1. InEquation 1, a fluid compliance attributable to the compressibility of anink in a pressure generation chamber is represented by Ci, a rigiditycompliance of materials themselves for an elastic plate and an ejectionhole plate each forming the pressure generation chamber is representedby Cv, inertance in an opening of an ejection hole is represented by Mn,and inertance in an ink supply port is represented by MS.

f=1/(2π)×√{square root over ( )}{(Mn+MS)/(Mn×MS)(Ci+Cv)}  Equation A

Further, in a liquid droplet ejection method using Helmholtz resonancevibration, frequency components of the resonance vibration representedby Equation A are controlled to thereby control ejection of liquiddroplets. That is, the resonance frequency f determined by Equation A isthe maximum drive frequency of a piezoelectric body, and frequencies arecontrolled based on the maximum drive frequency to thereby control theoperation of liquid droplet ejection.

Furthermore, besides the liquid droplet ejection method using Helmholtzresonance vibration, a liquid droplet ejecting method proposed in PTL 2is a liquid droplet ejecting method in which an ink in a liquid columnresonance-generating liquid chamber is ejected from ejection holes in alongitudinal direction of the liquid column resonance-generating liquidchamber, by utilizing a standing wave which generates in thelongitudinal direction of the liquid column resonance-generating liquidchamber.

However, according to the liquid droplet ejecting method disclosed inPTL 1 using Helmholtz resonance vibration, in order to a desiredresonance frequency, the accuracy of the fluid compliance for pressuregeneration chamber and the rigidity compliance must be increased.Unfavorably, the processing technique for pressure generation chamberhas a limitation on accuracy, and it is difficult to obtain a desiredresonance frequency. In addition, it is difficult to set the resonancefrequency high, and thus the liquid droplet ejecting method has aproblem that the liquid droplet diameter inversely proportional to theresonance frequency cannot be made small. Further, the liquid dropletejecting method disclosed in PTL 2 has a limit to eject microscopicliquid droplets using a high frequency, because the ejection holes aredisposed in the direction of propagation of the standing wave.

Next, the following describes background art relating to productionmethods of fine particles and fine particles using a fine particleproduction apparatus, in particular, toners.

Firstly, a pulverization method, which is one of toner productionmethods, is described by way of conventional resin fine particles. Thepulverization method is a typical toner production method that has beenconventionally employed, and a method in which a toner composition ismelt-kneaded by a two-roll or a biaxial extruder, and the melt-kneadedproduct is cooled, followed by a pulverization treatment of coarsepowder, a pulverization treatment of fine powder and a classificationtreatment, when required, a mixing treatment of external additives suchas a fluidizer by a HENSCHEL MIXER, etc. In the pulverization treatmentof coarse powder, a ROTOPLEX or pulverizer can be used. In thepulverization treatment of fine powder, a jet mill or turbo mill can beused. In the classification treatment, known production apparatuses suchas an ELBOWJET and a variety of air classifiers can be used.

There is a spray method as one of the conventional toner productionmethods other than the above-mentioned pulverization method. This spraymethod is a method in which a toner composition is formed into liquiddroplets in a vapor phase by using a single-fluid ejection hole(pressurization type ejection hole) sprayer which sprays a liquid fromejection holes by application of pressure, a multiple-fluid sprayejection hole sprayer which sprays a liquid and compressed gases in amixed form, a rotational disc type sprayer which forms a liquid intoliquid droplets by a centrifugal force using a rotating disc, or thelike. In the spray method, as a spray-dry system configured tosimultaneously perform spraying and drying, a commercially availabledevice can be used, however, when an ink cannot be sufficiently dried,secondary drying such as fluidized bed drying is performed, and whennecessary, mixing of external additives such as a fluidizer is performedusing a HENSCHEL MIXER etc.

Further, as a conventional toner production method other than thepulverization method, there is a jet granulation method. In the jetgranulation method, liquid droplets are ejected from ejection holes eachhaving a diameter as small as the diameter of toner using a vibrationgenerating unit, although a part of forming a liquid into droplets andsolidifying the droplets is the same as in the spray method.Conventionally, some jet granulation methods have been proposed. As oneof the jet granulation methods, PTL 3 proposed a toner productionmethod, in which the inside of a pressurization chamber is pressurizedto generate a liquid column from nozzles, the liquid column is brokeninto droplets by a weak ultrasonic vibration, and the droplets are driedand solidified to produce a toner, and a toner production apparatustherefor. Such a toner production apparatus generally includes a tonercomposition liquid-housing container to house a toner composition liquidto be supplied to a pressurization chamber in a liquid droplet jettingunit, and the toner composition liquid-housing container includes astirring member which stirs the toner composition liquid housed thereinto generate a flow. By generating a flow in the toner compositionliquid-housing container by the stirring member, respective materialscan maintain a uniformly dispersed state in the toner compositionliquid, and it is possible to prevent the respective materials frombeing dispersed with nonuniformity in the toner composition liquid.There is disclosed a toner production apparatus in which a tonercomposition liquid is pressurized to form a liquid column from throughholes, a weak vibration is applied to the liquid column by a vibrationgenerating unit to excite a Rayleigh fission, thereby forming uniformliquid droplets, followed by solidifying the liquid droplets, to therebyproduce toner base particles. In the method employing Rayleigh fission,a liquid is pressurized to be ejected, and thus the method has anadvantage in that the vibration generating unit is only required togenerate a weak vibration, and a toner composition liquid can be formedinto droplets with a low voltage.

However, the toner production method proposed in PTL3 utilizes Rayleighfission, and thus when a toner having a small diameter is produced, inorder to form liquid droplets having a particle size of about two-timesthe inner diameter of the ejection hole, the inner diameter of theejection hole should be made small. Further, this toner productionmethod has a problem that the liquid is pressurized in one direction,and toner components are clogged inside the nozzle depending on thecomposition of the toner.

In a head part disclosed in PTL4 as a still another example of a tonerproduction method using the jet granulation method, pulse-pressurizationis performed to uniformly pressurize the entire system of tonermaterials stored in a toner material reservoir part for storing thetoner materials, and thereby the toner materials are ejected fromejection holes. Hereinbelow, the principles of ejection of liquiddroplets disclosed in PTL4 are outlined with reference to FIGS. 32A to32E. In FIGS. 32A to 32E, pressure values inside a material reservoirpart (a) are described. In the liquid droplet ejecting method disclosedin PTL4, a toner composition liquid is effected to repeatedly behavethree states described below to thereby form liquid dropletsintermittently. As a first state, a head part is in a state where noejection signal is input, that is, as illustrated in FIG. 32A, in astate where no deformation occurs in a piezoelectric body (which may bereferred to as piezoelectric element) (b), causing no volume change in amaterial reservoir part (a), and a material liquid is not ejected froman ejection hole. Next, in a second state, an ejection signal is input,the piezoelectric body (b) undergoes displacement to the inside of thematerial reservoir part (a), and the material reservoir part (a)decreases as illustrated in FIGS. 32B and 32C. At this time, thepressure inside the material reservoir part (a) is momentarily increasedwith uniformity, and the material liquid is ejected from the ejectionhole. At this time, a flow of the materials is generated from thematerial reservoir part (a) to the side of a material housing part (notillustrated). Next, as a third state, after completion of the first timeejection of the materials, as illustrated in FIGS. 32D and 32E,application of the voltage is stopped, and the piezoelectric element (b)restores its substantially original shape. At this time, a negativepressure works in the material liquid, and the material liquid in anamount commensurate with an ejection amount is fed from a materialhousing part called a feeder for housing the material liquid to thematerial reservoir part (a).

However, since the liquid ejection method disclosed in PTL 4 is a methodof momentarily pressurizing the material liquid stored in the materialreservoir part (a) to intermittently eject the material liquid, there isa need to feed the material liquid reduced by a portion ejected in thethird state to the material reservoir part (a) to restore the firststate again where the material liquid is adequately stored. In view ofthe time spared for the third state and the overall production processtime, a time loss occurs, and the liquid ejection method has a problemthat the toner production efficiency corresponding to the time loss isreduced. Further, in the method disclosed in PTL4, generally, liquiddroplets large in size are inconveniently formed, and thus, in order toobtain a dry-process toner particle, the ejection part must be made tohave a small diameter or the materials must be diluted. However, whenthe ejection part is reduced in size, inevitably, the probability ofcausing clogging of a solid dispersion of a pigment which is essentiallyadded as a toner constituent element and a releasing agent etc. added asrequired dramatically increases, causing a problem with productionstability. In addition, when the toner material is diluted, the energyrequired for drying and solidifying the resulting diluent increases,which also greatly decreases the production efficiency. Furthermore, adecrease of the production efficiency prolongs the time for storing thematerial liquid in the material reservoir part, and a retention of thematerial liquid occurs, which may consequently cause sticking of thetoner material fractions in a long-term production period.

CITATION LIST Patent Literature

-   -   PTL 1 Japanese Patent (JP-B) No. 3569282    -   PTL 2 Japanese Patent (JP-B) No. 3234073    -   PTL 3 Japanese Patent Application Laid-Open (JP-A) No.        2007-199463    -   PTL 4 Japanese Patent (JP-B) No. 3786034

SUMMARY OF INVENTION Technical Problem

The present invention aims to solve the above-mentioned conventionalproblems and achieve the following object. That is, an object of thepresent invention is to provide a liquid droplet ejecting method and aliquid droplet ejection apparatus each of which enables setting adesired resonance frequency, irrespective of fluid compliance of aliquid chamber and rigidity compliance of components such as an ejectionhole plate, and producing extremely fine particle liquid droplets, andalso provide an inkjet recording apparatus capable of achievinghigh-density printing.

The present invention aims to solve the above-mentioned conventionalproblems and achieve the following object. That is, an object of thepresent invention is to provide a production method of fine particlesand a fine particle production apparatus each of which enables achievingcontinuous ejection of liquid owing to its ability of continuousdriving, thereby which assures extremely high productivity and enablesuniformly and stably producing extremely fine liquid droplets, and toprovide a toner.

Solution to Problem

Means for solving the above-mentioned problems are as follows:

<1> A liquid droplet ejecting method for ejecting a liquid from at leastone ejection hole to form the liquid into liquid droplets, the methodincluding:

applying a vibration to the liquid in a liquid columnresonance-generating liquid chamber, in which the ejection hole isformed, to form a standing wave through liquid column resonance, and

ejecting the liquid from the ejection hole, which is formed in a regioncorresponding to an antinode of the standing wave, to thereby form theliquid into the liquid droplets.

<2> The liquid droplet ejecting method according to <1>, wherein theejection hole is formed in plurality with respect to at least one regionwhich is the region corresponding to the antinode.<3> The liquid droplet ejecting method according to one of <1> and <2>,wherein the ejection hole is formed in plurality for each of the liquidcolumn resonance-generating liquid chambers.<4> The liquid droplet ejecting method according to any one of <1> to<3>, wherein at least part of both ends of the liquid columnresonance-generating liquid chamber in a longitudinal direction thereofis provided with a reflection wall surface.<5> The liquid droplet ejecting method according to any one of <1> to<4>, wherein a vibration having a frequency which satisfies Equation (1)below is applied to the liquid,

f=N×c/(4L)  Expression (1)

where L represents a length of the liquid column resonance-generatingliquid chamber in a longitudinal direction thereof, c represents a soundspeed of the liquid, and N is a natural number.

<6> The liquid droplet ejecting method according to any one of <1> to<4>, wherein a vibration having a frequency f which satisfies Expression(2) below is applied to the liquid,

N×c/(4L)≦f≦N×c/(4Le)  Expression (2)

where L represents a length of the liquid column resonance-generatingliquid chamber in a longitudinal direction thereof, Le represents adistance between the end of the liquid column resonance-generatingliquid chamber on the liquid feed path side and a center part of theejection hole nearest to the end of the liquid columnresonance-generating liquid chamber, c represents a sound speed of theliquid, and N is a natural number.

<7> The liquid droplet ejecting method according to <6>, wherein the Leand L satisfy Le/L>0.6.<8> The liquid droplet ejecting method according to any one of <1> to<4>, wherein a vibration having a frequency f which satisfies Expression(3) below is applied to the liquid,

N×c/(4L)≦f≦(N+1)×c/(4Le)  Expression (3)

where L represents a length of the liquid column resonance-generatingliquid chamber in a longitudinal direction thereof, Le represents adistance between the end of the liquid column resonance-generatingliquid chamber on the liquid feed path side and a center part of theejection hole nearest to the end of the liquid columnresonance-generating liquid chamber, c represents a sound speed of theliquid, and N is a natural number.

<9> The liquid droplet ejecting method according to any one of <1> to<8>, wherein the vibration is a high frequency vibration having afrequency of 300 kHz or higher.<10> The liquid droplet ejecting method according to any one of <5> to<8>, wherein a drive signal from a vibration generating unit excites thevibration generating unit by pulse groups which is primarily composed ofa liquid column resonance frequency depending on the length of theliquid column resonance-generating liquid chamber in the longitudinaldirection thereof.<11> The liquid droplet ejecting method according to <10>, wherein thepulse groups are divided into three pulse parts of a preparatorypressure generating pulse part, a drive main pulse part, and a residualvibration undoing pulse part,

wherein the preparatory pressure generating pulse part is present at aleading edge of the pulse groups and excites the liquid in the liquidcolumn resonance-generating liquid chamber to allow the liquid to remainin a state of not flying the liquid droplets, the drive main pulse partis an application pulse which follows the preparatory generating pulsepart and ejects the liquid from the ejection hole, and the residualvibration undoing pulse part is an application pulse immediately afterthe drive main pulse part and includes a frequency component having aphase opposite to that of a main frequency component of the drive mainpulse part.

<12> A liquid droplet ejection apparatus which ejects a liquid from atleast one ejection hole to form the liquid into liquid droplets, theapparatus including:

a liquid column resonance-generating liquid chamber in a part of whichthe ejection hole is formed, and

a vibration generating unit configured to apply a vibration to theliquid,

wherein the vibration is applied to the liquid in the liquid columnresonance-generating liquid chamber by the vibration generating unit toform a standing wave through liquid column resonance, and the liquid isejected from the ejection hole corresponding to an antinode of thestanding wave.

<13> An inkjet recording apparatus,

wherein the inkjet recording apparatus uses the liquid droplet ejectingmethod according to any one of <1> to <11>, or includes the liquiddroplet ejection apparatus according to <12>.

<14> A production method of fine particles, the production methodincluding:

ejecting a liquid from at least one ejection hole to form the liquidinto liquid droplets, and

solidifying the liquid droplets,

wherein the liquid contains a fine particle-forming component which isdissolved or dispersed in a solvent, or which is fused in the solvent,and

wherein the ejecting the liquid droplets is applying a vibration to theliquid in a liquid column resonance-generating liquid chamber, in whichthe ejection hole is formed, to form a standing wave through liquidcolumn resonance, and ejecting the liquid from the ejection hole whichis formed in a region corresponding to an antinode of the standing waveto thereby form the liquid into the liquid droplets.

<15> The production method of fine particles according to <14>, whereinthe fine particle-forming component is a resin or a resin composition.<16> The production method of fine particles according to one of <14>and <15>, wherein the ejection hole is formed in plurality with respectto at least one region, which is the region corresponding to theantinode.<17> The production method of fine particles according to any one of<14> to <16>, wherein the ejection hole is formed in plurality for eachof the liquid column resonance-generating liquid chambers.<18> The production method of fine particles according to any one of<14> to <17>, wherein at least part of both ends of the liquid columnresonance-generating liquid chamber in a longitudinal direction thereofis provided with a reflection wall surface.<19> The production method of fine particles according to any one of<14> to <18>, wherein a vibration having a frequency which satisfiesEquation (1) below is applied to the liquid,

f=N×c/(4L)  Expression (1)

where L represents a length of the liquid column resonance-generatingliquid chamber in a longitudinal direction thereof, c represents a soundspeed of the liquid, and N is a natural number.

<20> The production method of fine particles according to any one of<14> to <18>, wherein a vibration having a frequency f which satisfiesExpression (2) below is applied to the liquid,

N×c/(4L)≦f≦N×c/(4Le)  Expression (2)

where L represents a length of the liquid column resonance-generatingliquid chamber in a longitudinal direction thereof, Le represents adistance between the end of the liquid column resonance-generatingliquid chamber on the liquid feed path side and a center part of theejection hole nearest to the end of the liquid columnresonance-generating liquid chamber, c represents a sound speed of theliquid, and N is a natural number.

<21> The production method of fine particles according to <20>, whereinthe Le and L satisfy Le/L>0.6.<22> The production method of fine particles according to any one of<14> to <18>, wherein a vibration having a frequency f which satisfiesExpression (3) below is applied to the liquid,

N×c/(4L)≦f≦(N+1)×c/(4Le)  Expression (3)

where L represents a length of the liquid column resonance-generatingliquid chamber in a longitudinal direction thereof, Le represents adistance between the end of the liquid column resonance-generatingliquid chamber on the liquid feed path side and a center part of theejection hole nearest to the end of the liquid columnresonance-generating liquid chamber, c represents a sound speed of theliquid, and N is a natural number.

<23> The production method of fine particles according to any one of<14> to <22>, wherein the vibration is a high frequency vibration havinga frequency of 300 kHz or higher.<24> The production method of fine particles according to any one of<14> to <23>, wherein a flow path from which a gas for forming an airstream, which does not constrict a distance between ejected liquiddroplets, is flowed to a region where the solidifying of the liquiddroplets is provided.<25> The production method of fine particles according to <24>, whereinan initial ejection speed of the ejected droplets is lower than a speedof the air stream.<26> The production method of fine particles according to <14>, whereinthe liquid contains an organic solvent, and the solidifying of theliquid droplets is solidifying the liquid droplets by removing theorganic solvent so as to dry the liquid droplets.<27> A fine particle production apparatus including:

a liquid droplet ejecting unit configured to eject a liquid from atleast one ejection hole to form the liquid into liquid droplets, and

a solidifying unit configured to solidify the liquid droplets,

wherein the liquid contains a fine particle-forming component which isdissolved or dispersed in a solvent, or which is fused in the solvent,

a liquid column resonance-generating liquid chamber, in which theejection hole is formed, and

a vibration generating unit configured to apply a vibration to theliquid in the liquid column resonance-generating liquid chamber,

wherein the vibration is applied to the liquid in the liquid columnresonance-generating liquid chamber by the vibration generating unit toform a standing wave through liquid column resonance, and the liquid isejected from the ejection hole corresponding to an antinode of thestanding wave.

<28> A toner,

wherein the toner is obtained by the production method of fine particlesaccording to any one of <14> to <26> or the fine particle productionapparatus according to <27>.

<29> The toner according to <28>, wherein the toner has a particlediameter of 3.0 μm to 6.0 μm.

According to the present invention, a resonance phenomenon of generatinga resonance in a liquid column resonance-generating liquid chamber isutilized, and thus a drive voltage necessary for ejecting liquiddroplets can be set remarkably low, and a further higher-order resonancefrequency can be utilized, and thus ejection of liquid droplets can beachieved with an extremely high frequency. Further, since the frequencycan be set high, the diameter of liquid droplets ejected can be reducedinversely proportional to the frequency. Moreover, since differentstanding waves of a plurality of modes are present in an ejection headin the same structure, the frequency can be varied by using a pluralityof resonance modes as the situation demands, and the size of liquiddroplets to be formed can be changed.

In a fine particle production apparatus according to the presentinvention, ejection holes from which a toner composition liquid isejected are formed in a part of a liquid column resonance-generatingliquid chamber. The liquid column resonance-generating liquid chamber isprovided with a vibration generating unit configured to apply avibration to a composition liquid. When a high frequency suitable forresonance conditions is applied to the composition liquid, a standingwave through liquid column resonance is formed in the liquid columnresonance-generating liquid chamber. By the standing wave through theliquid column resonance, a pressure distribution is formed in the liquidcolumn resonance-generating liquid chamber. In the standing wave throughthe liquid column resonance generated in the liquid columnresonance-generating liquid chamber, there is an area for the pressuredistribution called “antinode”, in which a high pressure is generated.By providing the ejection hole in the area for the pressure distributioncorresponding to the antinode, a high pressure is applied to thecomposition liquid near the ejection hole, and thereby the compositionliquid is continuously ejected. Subsequently, by solidifying the tonerliquid droplets formed, toner particles are produced. With the processdescribed above, continuous ejection of toner liquid droplets can beachieved, and extremely high productivity can be expected.

As described above, the liquid droplet ejection method of the presentinvention can achieve continuous liquid droplet ejection at highfrequency and has an excellent effect that extremely high productivitycan be expected.

Advantageous Effects of Invention

The present invention can solve the above-mentioned conventionalproblems and achieve the object described above. That is, the presentinvention can provide a liquid droplet ejecting method and a liquiddroplet ejection apparatus each of which enables setting a desiredresonance frequency, irrespective of fluid compliance of a liquidchamber and rigidity compliance of components such as an ejection holeplate, and producing extremely fine particle liquid droplets, and alsoprovide an inkjet recording apparatus capable of achieving high-densityprinting.

Also, the present invention can solve the above-mentioned conventionalproblems and achieve the object described above. That is, the presentinvention can provide a production method of fine particles and a fineparticle production apparatus each of which enables achieving continuousejection of liquid owing to its ability of continuous driving, therebywhich assures extremely high productivity and enables uniformly andstably producing extremely fine liquid droplets, and to provide a toner.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional diagram illustrating a configuration of aliquid droplet ejection head of a liquid droplet ejection apparatusaccording to one example of the present invention.

FIG. 2A is a diagram illustrating the shape of a standing wave effectedby a speed/pressure variation when N is a natural number of 1.

FIG. 2B is a diagram illustrating the shape of a standing wave effectedby a speed/pressure variation when N is a natural number of 2.

FIG. 2C is a diagram illustrating the shape of another standing waveeffected by a speed/pressure variation when N is a natural number of 2.

FIG. 2D is a diagram illustrating the shape of a standing wave effectedby a speed/pressure variation when N is a natural number of 3.

FIG. 3A is a diagram illustrating the shape of a standing wave effectedby a speed/pressure variation when N is a natural number of 4.

FIG. 3B is a diagram illustrating the shape of another standing waveeffected by a speed/pressure variation when N is a natural number of 4.

FIG. 3C is a diagram illustrating the shape of a standing wave effectedby a speed/pressure variation when N is a natural number of 5.

FIG. 4 is a schematic diagram illustrating the appearance of a liquidcolumn resonance phenomenon in a liquid column resonance-generatingliquid chamber of a liquid ejection head.

FIG. 5 is a diagram illustrating one example of an image of ejection ofliquid droplets having a 300 kHz-sine wave obtained by a lasershadowgraph method.

FIG. 6 is a characteristic graph illustrating a relationship between adrive frequency and an ejection speed.

FIG. 7A is a schematic diagram illustrating the appearance of a liquidcolumn resonance phenomenon generated in a liquid columnresonance-generating liquid chamber of a liquid ejection head.

FIG. 7B is another schematic diagram illustrating the appearance of aliquid column resonance phenomenon generated in a liquid columnresonance-generating liquid chamber of a liquid ejection head.

FIG. 7C is still another schematic diagram illustrating the appearanceof a liquid column resonance phenomenon generated in a liquid columnresonance-generating liquid chamber of a liquid ejection head.

FIG. 7D is yet still another schematic diagram illustrating theappearance of a liquid column resonance phenomenon generated in a liquidcolumn resonance-generating liquid chamber of a liquid ejection head.

FIG. 7E is further yet still another schematic diagram illustrating theappearance of a liquid column resonance phenomenon generated in a liquidcolumn resonance-generating liquid chamber of a liquid ejection head.

FIG. 8A is a diagram illustrating the appearance of liquid dropletejection per drive frequency.

FIG. 8B is another diagram illustrating the appearance of liquid dropletejection per drive frequency.

FIG. 9A is a waveform diagram illustrating a drive voltage wave.

FIG. 9B is another waveform diagram illustrating a drive voltage wave.

FIG. 10 is a wave diagram illustrating a drive voltage waveformincluding a preparatory generation pulse part.

FIG. 11 is a characteristic graph illustrating a relationship between apressure applied per drive frequency and a volume of liquid droplets.

FIG. 12 is a schematic cross-sectional diagram illustrating theconfiguration of an inkjet recording apparatus.

FIG. 13 is a cross-sectional diagram illustrating the overallconfiguration of a toner production apparatus according to oneembodiment of the present invention.

FIG. 14 is a cross-sectional diagram illustrating the configuration ofthe liquid droplet ejection head in the liquid droplet forming unit(liquid droplet ejection apparatus) in FIG. 13.

FIG. 15 is an A-A′ line cross-sectional diagram illustrating theconfiguration of the liquid droplet forming unit in FIG. 13.

FIG. 16 is a diagram illustrating the appearance of actual liquiddroplet ejection.

FIG. 17 is a characteristic graph illustrating a relationship between adrive frequency and a liquid droplet ejection speed.

FIG. 18 is a characteristic graph illustrating a relationship between avoltage applied and an ejection speed in each ejection hole.

FIG. 19 is a characteristic graph illustrating a relationship between avoltage applied and a diameter of a liquid droplet.

FIGS. 20A and 20B are diagrams illustrating an example of a liquiddroplet ejection head.

FIGS. 21A and 21B are diagrams illustrating another example of a liquiddroplet ejection head.

FIGS. 22A and 22B are diagrams illustrating still another example of aliquid droplet ejection head.

FIGS. 23A and 23B are diagrams illustrating yet still another example ofa liquid droplet ejection head.

FIGS. 24A and 24B are diagrams illustrating yet still another example ofa liquid droplet ejection head.

FIGS. 25A and 26B are diagrams illustrating yet still another example ofa liquid droplet ejection head.

FIGS. 27A and 27B are diagrams illustrating yet still another example ofa liquid droplet ejection head.

FIGS. 28A and 28B are diagrams illustrating yet still another example ofa liquid droplet ejection head.

FIGS. 29A and 29B are diagrams illustrating yet still another example ofa liquid droplet ejection head.

FIG. 30 is a diagram illustrating yet still another example of a liquiddroplet ejection head.

FIG. 31 is a cross-sectional diagram illustrating still anotherconfiguration of a liquid droplet ejection head in a liquid dropletforming unit.

FIGS. 32A to 32E are each cross-sectional diagram illustrating theappearance of liquid droplet behavior in a toner liquid droplet head ina conventional toner production apparatus.

DESCRIPTION OF EMBODIMENTS

Firstly, the mechanism of formation of liquid droplets in a liquiddroplet ejection apparatus, and a fine particle production apparatus ofthe present invention will be described below.

FIG. 1 is a cross-sectional diagram illustrating a configuration of aliquid droplet ejection head of a liquid droplet ejection apparatusaccording to one example of the present invention. Specifically, thefollowing describes the principle of a liquid column resonancephenomenon generated in a liquid column resonance-generating liquidchamber 18 in a liquid droplet ejection head 11 in FIG. 1. When a soundspeed of a liquid in a liquid column resonance-generating liquid chamber18 is represented by c, and a drive frequency applied to the liquid(medium) from a vibration generating unit 20 is represented by f, awavelength 2 at which resonance of the liquid is generated satisfies thefollowing Equation B.

λ=c/f  Equation B

In the liquid column resonance-generating liquid chamber 18 in FIG. 1,in the case where both ends are fixed, in which a length from an edge ofa frame on a fixed edge side to the other edge thereof on the side of aliquid supply path 16 is represented by L, further, a height h1 (=about80 [μm]) of an edge of the frame on a liquid supply path 16 is aboutdouble the height h2 (=about 40 [μm]) of a communication hole, and theheight of this edge is equal to the fixed edge in a closed state, thelength L meets an even number times the one fourth (¼) of the wavelengthλ, resonance is most efficiently formed. That is, the length L isrepresented by the following Equation C.

L=(N/4)λ  Equation C

(where N is an even number)

Also, in the case where both ends are completely open, Equation C isestablished.

Similarly, in the case where an open end to which a pressure is escapedis provided at one end and the other end is closed (fixed end), i.e., inthe case of one-end-fixed or one-end-opened, the resonance is mostefficiently formed when the length L meets odd number time times theone-fourth of a wavelength λ. That is, N in Equation C is represented byan odd number.

A drive frequency exhibiting the most efficiency f is derived fromEquation B and Equation C.

f=N×c/(4L)  Expression (1)

However, actually, a liquid has a viscosity attenuating a resonance, andthus a vibration does not endlessly amplitude. Even with a frequencyclose to the high-drive frequency f exhibiting most efficiency as shownin Equation 1, a resonance is generated.

In FIGS. 2A to 2D, a shape (resonance mode) of a standing wave formeddepending on variations of the speed and pressure in the case of N isequal to 1, 2, or 3 (in FIG. 2A, N=1, L=λ/4; in FIG. 2B, N=2, L=λ/2, inFIG. 2C, N=2, L=λ/2, and in FIG. 2D, N=3, L=3λ/4). In FIGS. 3A to 3D, ashape (resonance mode) of a standing wave formed depending on variationsof the speed and pressure in the case of N is equal to 4 or 5 (in FIG.3A, N=4, L=λ; in FIG. 3B, N=4, L=λ, and in FIG. 3C, N=5, L=5λ/4).Essentially, the standing wave is a compressional wave (longitudinalwave), however, it is generated represented as illustrated in FIGS. 2Ato 2D and 3A to 3C. In these figures, a solid line is a standing wave ofthe speed, and a dotted line is a standing wave of the pressure applied.For example, as can be seen from FIG. 2A illustrating the case ofone-end fixed, with N=1, in the case of a speed distribution, a closedend is provided, and the amplitude of the speed distribution becomeszero. The amplitude becomes a maximum at the open end, which isintuitively understandable with ease. When the length of the liquidcolumn resonance-generating liquid chamber in the longitudinal directionthereof is represented by L, a wavelength at which the liquid causes aliquid-column resonance is represented by λ, a standing wave is mostefficiently generated, provided that the integer N is 1 to 5. Further, astanding wave pattern differs depending on a closed-or-open state of theboth side, and these different pattern are also described herein.Depending on the aperture of ejection holes and the state of theaperture of ejection holes on the feed path side, the conditions for theends are determined. Note that in acoustics, an aperture end is an endwith which the transfer speed of a medium (liquid) in the longitudinaldirection is a maximum, and inversely, the pressure is zero. Incontrast, a closed end is defined as an end at which the transfer speedof a medium becomes zero. A closed end is considered as a hard wall fromthe standpoint of acoustics and in the closed end, reflection of a waveoccurs. When it is ideally completely closed or opened, a standing wavethrough liquid column resonance in the form as illustrated in FIGS. 2Ato 2D and 3A to 3C, is generated by super-position of waves, however,the standing wave pattern varies depending on the number of liquiddroplet ejection holes, and the aperture position of the liquid dropletejection holes. A resonance frequency appears at a position shifted froma position determined by Equation 1, and conditions for stable ejectioncan be created by appropriately adjusting the drive frequency. Forexample, when a sound speed c of a liquid: 1,200 m/s, a and a length Lof a liquid column resonance-generating liquid chamber: 1.85 mm, andwall surfaces are present at both sides, and a resonance mode N=2, whichis completely equal to the case where both ends are fixed ends, areused, a resonance frequency having the highest in efficiently is derivedas 324 kHz from Equation C. In another example, when a sound speed c ofa liquid: 1,200 m/s, a and a length L of a liquid columnresonance-generating liquid chamber: 1.85 mm each of which is the sameconditions as the above-mentioned example, and wall surfaces are presentat both sides, and a resonance mode N=4, which is completely equal tothe case where both ends are fixed ends, are used, a resonance frequencyhaving the highest in efficiently is derived as 648 kHz fromExpression 1. In a liquid column resonance-generating liquid chamberhaving the same configuration as described above, a higher-orderresonance can also be utilized.

Note that the liquid column resonance-generating liquid chamber in theliquid droplet ejection head according to the present embodimentillustrated in FIG. 1 preferably has ends in a closed state, which areequal to each other, or an end which can be illustrated as aacoustically soft wall in order to increase the frequency, because ofthe influence of the ejection holes 19 however, the ends may be in anopen state. Here, the influence of aperture of ejection holes 19 meansthat particularly, an acoustic impedance is decreased, and a compliancecomponent is increased. Therefore, a configuration of a liquid columnresonance-generating liquid chamber having wall surfaces at both sidesthereof in a longitudinal direction thereof as illustrated in FIG. 2Band FIG. 3A, all resonance modes including a resonance mode of both-endsfixed, and one-side open end where the liquid droplet ejection holessize are regarded as open aperture can be utilized, and thus it is apreferred configuration.

When a voltage is applied to a piezoelectric element at a drivefrequency determined as described above, the piezoelectric element isdeformed, and a standing wave of pressure is generated in a drive cycle.In the liquid ejection head according to the present embodiment usingsuch a principle, a standing wave through liquid column resonance isformed in a liquid column resonance-generating liquid chamber 18, andliquid droplets 21 are continuously ejected from ejection holes 19 whichare arranged on part of the liquid column resonance-generating liquidchamber 18.

Note that it is preferable in terms of efficiency that the ejectionholes 19 be arranged in a region corresponding to an antinode of thestanding wave through liquid column resonance. The “region correspondingto an antinode of the standing wave through liquid column resonance”means a region other than nodes of the standing wave. Preferably, theregion is a region having such a large amplitude by which the liquid isejected by a change in pressure to the standing wave. More preferably,the region is a region within a range of ±¼ wavelength from a positionwhere the amplitude of the pressure standing wave becomes a maximum (anode for a speed standing wave) toward a position where the amplitude ofthe pressure standing wave becomes a minimum (see FIG. 4, where Arepresents a wave surface; Z represents a node of a pressure; Xrepresents an antinode of a pressure at a −¼ wavelength from the maximumvalue; and Y represents an antinode of a pressure at a +¼ wavelengthfrom the maximum value). When the ejection holes are formed in theregion corresponding to an antinode of the standing wave, substantiallyuniform liquid droplets can be formed from respective ejection holes,even when the ejection holes are formed in plurality, and ejection ofholes can be performed efficiently. In addition, clogging of ejectionholes hardly occurs. One ejection hole 19 may be formed for one liquidcolumn resonance-generating liquid chamber, however, it is preferable toform a plurality of ejection holes (the ejection holes 19) from the viewpoint of productivity. Specifically, the number of ejection holes ispreferably in a range of 2 to 100. When the number of ejection holesexceeds 100, there is a need to set a voltage applied to thepiezoelectric element high in an attempt to form liquid droplets in adesired form from 100 pieces of the ejection holes and the behavior ofthe piezoelectric element becomes unstable.

In addition, when a plurality of the ejection holes 19 are formed, apitch between the liquid droplet ejection holes is preferably 20 μm orgreater and equal to or smaller than the length of the liquid columnresonance-generating liquid chamber 18. When the pitch between theliquid droplet ejection holes is smaller than 20 μm, there is a highprobability that liquid droplets discharged from adjacent ejection holes19 collide with each other to be a large-size droplet.

Further, the numerical aperture of the liquid droplet ejection holes,arrangement of position for the aperture of the ejection holes and thecross-sectional shape of the liquid droplet ejection holes will alsobecome factors to determine the drive frequency, and the drive frequencycan be suitably determined in accordance with these conditions. Forexample, when the number of liquid ejection holes is increased, therestriction of a leading edge of the liquid column resonance-generatingchamber, which was a fixed end initially, was gradually loosened, and aresonance standing wave close to a standing wave obtained at asubstantially open end occurs, and the drive frequency increases.Furthermore, the restriction conditions are loosened from the positionof the ejection holes present the nearest to the liquid feed path sideas a start point, and the cross-sectional shape of the liquid dropletejection holes becomes a round shape, the volume of ejection holesvaries due to the thickness of a frame employed, an actual standing wavebecomes to have a short wavelength and higher than the drive frequencyemployed.

The liquid column resonance phenomenon generated in the longitudinaldirection of the liquid column resonance-generating liquid chamber 18 isa phenomenon in which a standing wave is generated to a length L of theliquid column resonance-generating liquid chamber 18 in the longitudinaldirection thereof, and a pressure vibration is amplified at a specificfrequency. A system employing this ejection method has a sufficient sizeto ensure the quantity of ejection, and is a pressure flow path which isessentially long for accumulation or collection of droplets at ejectionholes.

Note that the liquid column resonance-generating liquid chamber 18 in aliquid droplet ejection head 11 is formed to joint a frame formed of amaterial having such high rigidity that does not adversely influenceupon the resonance frequency of the liquid, such as metal, ceramics, andsilicon. As illustrated in FIG. 1, a length L between wall surfacesprovided at both ends of a liquid column resonance-generating liquidchamber 18 in the longitudinal direction thereof is determined based onExpression 1, and after-mentioned Expressions 2 and 3. A flow path forsupply of a liquid is formed for each of the liquid columnresonance-generating chambers, from the liquid feed path 16, and theliquid feed path 16 is continuously connected to a plurality of liquidcolumn resonance-generating liquid chambers 18.

In addition a vibration generating unit 20 in the liquid dropletejection head 11 is not particularly limited as long as it can drive ata given frequency. Such an aspect is desired in which a piezoelectricelement is laminated to an elastic plate. The elastic plate constitutespart of the wall in the liquid column resonance-generating chamber sothat the piezoelectric element comes into contact with the liquid.Examples of material for the elastic plate include piezoelectricceramics such as lead zirconate titanate (PZT). Generally, since such amaterial has a small amount of displacement, in most cases, it is usedin a laminate form. Besides, piezoelectric polymers such aspolyvinylidene fluoride (PVDF), crystal, and single crystal such asLiNbO₃, LiTaO₃, KNbO₃ are exemplified. Furthermore, the vibrationgenerating unit 20 is desirably disposed so that it can be individuallycontrolled for each liquid column resonance chamber. In addition, thefollowing configuration is desired: one material selected from thosedescribed above in a block shape is partially cut to fit the arrangementof the liquid column resonance-generating chamber, and respective liquidcolumn resonance-generating chambers can be controlled individually, viaan elastic plate.

Further, a voltage is applied to the vibration generating unit with thedetermined drive frequency, the vibration generating unit is deformed,and a resonance standing wave is most efficiently generated at the drivefrequency. Furthermore, with a frequency close to the drive frequency atwhich the resonance standing wave is most efficiently generated, aliquid column resonance standing wave is generated. That is, when thevibration generating unit is effected to vibrate using a drive waveformprimarily containing a drive frequency f in a range determined by thefollowing Expressions 2 and 3 using both lengths of L and Le, where alength between both ends of the liquid column resonance-generatingliquid chamber in a longitudinal direction thereof is represented by L,and a distance between the end of the liquid column resonance-generatingliquid chamber on the liquid feed side and a center of a liquid dropletejection hole nearest to the end of the liquid columnresonance-generating liquid chamber on the liquid feed side isrepresented by Le, to excite liquid column resonance, and thereby liquiddroplets can be ejected from ejection holes.

N×c/(4L)≦f≦N×c/(4Le)  Expression (2)

N×c/(4L)≦f≦(N+1)×c/(4Le)  Expression (3)

Note that a ratio Le/L, i.e., the distance Le between the end of theliquid column resonance-generating liquid chamber on the liquid feedside and a center portion of a liquid droplet ejection hole nearest tothe end of the liquid column resonance-generating liquid chamber on theliquid feed side with respect to the length L between both ends of theliquid column resonance-generating liquid chamber in its longitudinaldirection is preferably greater than 0.6, i.e., Le/L>0.6.

FIG. 5 illustrates an example of an image of ejection of a sine wave at300 kHz, which was photographed by laser shadowgraphy. In this example,ejection of liquid droplets having extremely uniform diameters isachieved with a substantially uniform ejection speed. FIG. 6 illustratesa frequency characteristic of liquid droplets when a vibrationgenerating unit is driven with an amplitude sine wave at 255 k Hz to 350kHz. The ejection speed becomes uniform particularly in the vicinity ofa peaked position (300 kHz). This shows that uniform ejection is surelyachieved at a position corresponding to an antinode of a pressurestanding wave in the vicinity of 300 kHz, which is the second mode of aliquid column resonance frequency.

Next, appearance of liquid column resonance phenomenon generated in aliquid column resonance-generating chamber in a liquid droplet ejectionhead will be described with reference to FIGS. 7A to 7E. Note that, inFIGS. 7A to 7E, a solid line written in a liquid columnresonance-generating liquid chamber represents a speed distributionwhich is obtained by plotting a speed measured at each measurementposition arbitrarily selected from a fixed end side of the liquid columnresonance-generating liquid chamber to an end of the liquid columnresonance-generating liquid chamber on the liquid feed side, a directionfrom the liquid feed side toward the liquid column resonance-generatingliquid chamber is defined as + (plus), and the opposite direction isdefined as − (minus). In addition, in FIGS. 7A to 7E, a dotted linewritten in the liquid column resonance-generating liquid chamberrepresents a pressure distribution which is obtained by plotting apressure value measured at each measurement position arbitrarilyselected from the fixed end side of the liquid columnresonance-generating liquid chamber to the end of the liquid columnresonance-generating liquid chamber on the liquid feed side, a positivepressure with respect to atmospheric pressure is defined as + (plus),and a negative pressure with respect to atmospheric pressure is definedas − (minus). When the pressure is a positive pressure, the pressure isapplied in a downward direction in the figures, whereas, when thepressure is a negative pressure, the pressure is applied in an upwarddirection in the figures. In addition, in FIGS. 7A to 7E, the liquidcolumn resonance-generating liquid chamber is opened on the liquid feedpath 16 side, as described above. Since the height of a frame serving asthe fixed end of the liquid column resonance-generating liquid chamberis approximately twice or more than the height of an aperture in whichthe liquid feed path 16 is in communication with the liquid columnresonance-generating liquid chamber 18, there are illustrated a speeddistribution and a pressure distribution which vary with time underapproximate conditions where the liquid column resonance-generatingliquid chamber 18 has substantially fixed both ends.

FIG. 7A illustrates a pressure waveform and a speed waveform in theliquid column resonance-generating liquid chamber 18 when liquiddroplets are ejected. FIG. 7B illustrates a pressure waveform and aspeed waveform in the liquid column resonance-generating liquid chamber18 when a liquid is fed in the liquid column resonance-generating liquidchamber 18 immediately after the ejection of liquid droplets. Asillustrated in FIGS. 7A and 7B, a pressure in the liquid columnresonance-generating liquid chamber 18 in which ejection holes 19 areformed is a maximum. The liquid the liquid column resonance-generatingliquid chamber 18 flows to the liquid feed path 16 side, and the flowspeed (rate) is low. Subsequently, as illustrated in FIG. 7C, a positivepressure in the vicinity of the ejection holes 19 is decreased, andtransfers toward a negative pressure direction. The direction to whichthe liquid flows in the liquid column resonance-generating liquidchamber 18 is the same as illustrated in FIGS. 7A and 7B, i.e., theliquid flows toward the liquid feed path 16 side, however, the flowspeed becomes a maximum.

Further, as illustrated in FIG. 7D, the pressure in the vicinity of theejection holes 19 becomes a minimum. The flow of the liquid in theliquid column resonance-generating liquid chamber 18 changes from theliquid feed path 16 side toward the liquid column resonance-generatingliquid chamber 18. The flow speed is low. From this point in time,refilling of the liquid column resonance-generating liquid chamber 18with the liquid begins. Subsequently, as illustrated in FIG. 17E, thenegative pressure in the vicinity of the ejection holes 19 becomessmall, and transfers toward a positive direction. The direction to whichthe liquid flows in the liquid column resonance-generating liquidchamber 18 is the same as illustrated in FIG. 7D, i.e., the liquid flowstoward the liquid feed path 16 side, however, the flow speed becomes amaximum. At this point in time, the refilling of the liquid finished.Then, as illustrated in FIG. 7A, the positive pressure in a liquiddroplet ejection area in the liquid column resonance-generating liquidchamber 18 becomes a maximum again, liquid droplets 21 are ejected fromthe ejection holes 19. In this way, in a liquid columnresonance-generating liquid chamber, a standing wave through liquidcolumn resonance takes place by a high frequency drive from a vibrationgenerating unit, and because the ejection holes 19 are arranged in aregion corresponding to an antinode of the standing wave through liquidcolumn resonance, which is a region where the pressure most greatlyvaries, the liquid droplets 21 are ejected from the ejection holes 19according to the cycle of the antinode.

FIG. 8A illustrates the appearance of liquid droplet ejection at a drivefrequency of 115 kHz, and FIG. 8B illustrated the appearance of liquiddroplet ejection at a drive frequency of 300 kHz. As compared to theliquid droplet ejection illustrated in FIG. 8A where the drive frequencyis 115 kHz, it is verified that in the liquid droplet ejection at adrive frequency of 300 kHz as illustrated in FIG. 8B, the speed and thediameter of liquid droplets tends to monotonously increase relative toan increase in voltage.

FIG. 9 is a diagram for illustrating a waveform of a drive voltageapplied to a piezoelectric element serving as a pressure generatingmember in a liquid droplet ejection apparatus according to the presentinvention. In reference to a voltage applied to the piezoelectricelement, a frequency-corresponding waveform as illustrated in FIGS. 8Aand 8B is applied. As described above, a drive voltage waveform includesa continuous pulse group primarily containing liquid column resonancefrequencies of a liquid in a liquid column resonance-generating liquidchamber. The liquid column frequencies include a plurality of resonancemode fractions, which can be suitably used. A plurality of liquiddroplets is effected to fly with a plurality of pulses, and one pixel isformed with the plurality of liquid droplets. At this time, the numberof pulses is not necessarily the same as the number of liquid dropletsejected. In addition, by controlling the number of pulses in acontinuous pulse group to be driven, the number of liquid droplets to beejected, i.e., the quantity of liquid droplets is mage variable.Therefore, the diameter of pixel can be multi-valued on a recordingmedium, and recording with image gradation properties is facilitated.

Furthermore, in order to accurately control the liquid droplet ejectionquantity and ejection timing, it is desirable to give a frequencycorresponding waveform as described below. A continuous pulse group forforming one pixel is designed to include three divided pulse parts: apreparatory pressure generating part as illustrated in FIG. 10 (awaveform during a period of (a) in FIG. 10), a drive main pulse part (awaveform during a period of (b) in FIG. 10), and a residual vibrationundoing pulse part (a waveform during a period of (c) in FIG. 10). Thepreparatory pressure generating part is present at a leading edge of thecontinues pulse group, and allows the liquid inside the liquid columnresonance-generating liquid chamber to remain in a state of not flyingliquid droplets and increases the pressure to the liquid in the vicinityof an ejection hole. In other words, the preparatory pressure generatingpart prevents liquid leak and inhalation of air bubbles. The drive mainpulse part follows the preparatory pressure generating part and fliesliquid droplets according to a pulse applied. The control of the liquiddroplet quantity is performed in this part. Note that the pulse groupincludes liquid resonance frequencies of the liquid in the liquid columnresonance-generating liquid chamber as a main component. The residualvibration undoing pulse part is an application pulse which applies afrequency component having a phase opposite to that of a main frequencycomponent of the drive main pulse part immediately after the drive mainpulse part to thereby rapidly reduce the pressure applied to the liquidin the liquid column resonance-generating liquid chamber. With thisconfiguration, when a subsequent continuous pulse group is applied tothe liquid, the pressure applied to the liquid in the vicinity of theejection hole and a meniscus phase of the liquid in the ejection holecan be restored to the initial condition. That is, it is possible toincrease the response frequency of the drive pulse group.

A series of drive voltage waveforms are not limited to sine waveforms asillustrated in FIGS. 9A and 9B, and may be rectangular waves or pulsewaves, as long as the frequency components primarily contain theabove-mentioned liquid resonance frequencies of the liquid in the liquidcolumn resonance-generating chamber. Actually, a waveform itself causesa delay with a time constant in accordance with the capacity componentof a piezoelectric element itself serving as a pressure generatingmember, at a start point and a fall point, and thus it is possible toobtain sufficient practicability with a rectangular pulse wave.Moreover, in the preparatory pressure generating part, only the voltagelevel can be set low with the same frequency component as in the drivemain pulse part as illustrated in FIG. 10, and only the frequencycomponent can be set varied with the same voltage level as in the drivemain pulse part as illustrated in FIG. 9. The also applies to theresidual vibration undoing pulse part.

As described above, a liquid resonance frequency for use in a drive mainpulse part is 300 kHz (approximately 3 μs) or less, and thus it isadvisable that one pixel be designed to include about one droplet toabout 10 droplets and an actual drive frequency be set to about 30 KHzto thereby obtain a multiple tone.

As having been described above, a liquid droplet ejection head accordingto the present embodiment utilizes a fluid liquid resonance of a liquid,not directly converting the displacement amount of a pressure generationmember into a volume displacement in the liquid chamber to eject liquiddroplets, and thus the amount of drive energy can be remarkably reduced.

Next, the mechanism part of an inkjet recording apparatus serving as aliquid droplet ejection apparatus according to the present inventionwill be described below, with reference to FIG. 12.

In an inkjet recording apparatus 100 illustrated in FIG. 12, a carriage103 was kept slidably in a main scanning direction by a guide rod 101serving a guide member laid across on lateral plates (not illustrated)and a stay 102. Scanning is performed by a main scanning motor (notillustrated). In the carriage 103, a recording head 104 including fourinkjet recording heads which discharge recording ink drops forrespective colors, yellow (Y), cyan (C), magenta (M), and black (Bk) isloaded, so that a plurality of ink discharge openings is arranged in thedirection crossing the main scanning direction, and ink drop dischargedirection is headed below.

The recording head 104 based on a liquid column resonance includes twoejection hole rows for each, in which one ejection hole row of therecording head ejects black (K) liquid droplets, and the other sideejection hole row ejects cyan (C) liquid droplets. In the other ejectionhole row of the recording head, one ejection hole row ejects magenta (M)liquid droplets, and the other side ejection hole row ejects yellow (Y)liquid droplets.

The carriage 103 is provided with a head tank 105 serving as a liquidhousing container for feeding each color ink corresponding to each ofthe ejection hole rows in the recording head 104. In the head tanks 105,each color ink is replenished and supplied from respective inkcartridges for each color, which are mounted on a cartridge loading part(not illustrated) via ink supply tubes for each color (not illustrated).In the cartridge mounting part, a feed pump unit (not illustrated) forliquid feeding of each color ink in the individual ink cartridge isdisposed.

Meanwhile, as a paper feed part to feed paper 108 laded on a paperlading section (pressure plate) 107 of the paper feed tray 106, thereare provided a semilunar roller (paper feed roller 109) which separatelyfeed the paper 108 piece by piece from the paper lading section 107 anda separation pad 110 made of a material having a large frictioncoefficient, which faces the paper feed roller 109. This separation pad110 is biased toward the paper feed roller 109 side.

As a conveyance part to convey the paper 108 fed from this paper feedpart below the recording head 104, a guide member 111 to guide the paper108, a counter roller 112, a conveyance guide member 113, and a pressmember 115 having a leading edge pressure roller 114 and a conveyancebelt 116 to electrostatically absorb and convey the paper 108 at aposition facing the recording head 104 are provided. The conveyance belt116 is an endless belt. The conveyance belt 116 is stretched between aconveyance roller 117 and a tension roller 118, and can go around in thebelt conveyance direction. Further, a charging roller 119 which is anelectrification measure to charge a surface of the conveyance belt 116is provided. The charging roller 119 is disposed so that it is incontact with the surface of the conveyance belt 116 so that it is drivento rotate according to the rotation of the conveyance belt 116. Theconveyance belt 116 moves around in the belt conveyance direction byrotatably driving the conveyance roller 117 at an appropriate timing byan unillustrated sub-scanning motor.

As a paper ejection part to eject the paper 108 recorded by therecording head 104, a separation claw 120 to separate the paper 108 fromthe conveyance belt 116, a paper ejection roller 121, and a paperejection roller 122 are provided, and the paper ejection tray 123 isarranged below the paper ejection roller 121.

A double-sided paper feed unit 124 is detachably loaded on the rear facepart of the apparatus body. The double-sided paper feed unit 124 takesin the paper 108 returned by backward rotation of the conveyance belt116, inverts the paper 108, and feeds the paper 108 again between thecounter roller 112 and the conveyance belt 116. A manual paper feedsection 125 is provided on the top face of the double-sided paper feedunit 124.

As having been described above, according the present embodiment, when avibration is applied to the liquid in the liquid columnresonance-generating liquid chamber 18 illustrated in FIG. 1 by thevibration generating unit 20, a standing wave through liquid columnresonance is generated. A pressure distribution is formed in the liquidcolumn resonance-generating liquid chamber utilizing the standing wavethrough liquid column resonance. The liquid is ejected from the ejectionholes by a change in the pressure distribution formed. Therefore, theresonance frequency excited by the liquid column resonance can be set toa desired frequency, irrespective of the structure of a liquid chamberin a conventional liquid droplet ejecting method. In addition, liquiddroplets having an extremely fine particle diameter, which is inverselyproportional to the frequency, can be ejected by setting the resonancefrequency high.

Further, the ejection holes 19 are formed in a region corresponding toan antinode of the standing wave through the liquid column resonanceformed in the resonance-generating liquid chamber 18 in a memberconstituting the resonance-generating liquid chamber 18

Furthermore, a plurality of the ejection holes 19 are formed for oneliquid column resonance-generating liquid chamber 18. With this, liquiddroplets can be ejected with high density.

At both ends of the liquid column resonance-generating liquid chamber 18in a longitudinal direction thereof, as illustrated in FIG. 1, areflection wall surface is provided at least a part of the ends.Therefore, the liquid column resonance-generating liquid chamber is madeto have at least one-end fixed end. A standing from through liquidcolumn resonance formed in the liquid column resonance-generating liquidchamber is a stable waveform, and stable ejection of liquid droplets canbe expected.

Further, the vibration generating unit 20 is effected to vibrate using adrive waveform primarily containing a frequency f which is determined byusing L and Le and which satisfies N×c/(4L)≦f≦N×c/(4Le) where Lrepresents a length of the liquid column resonance-generating liquidchamber 18 in a longitudinal direction thereof, Le represents a distancebetween the end of the liquid column resonance-generating liquid chamber18 on the liquid feed path side and a center part of the ejection hole19 nearest to the end of the liquid column resonance-generating liquidchamber 18, on the side of the liquid feed path 16 which is continuouslyconnected to the liquid column resonance-generating liquid chamber 18, afrequency of a high frequency vibration generated by the vibrationgenerating unit 20 is represented by f, c represents a sound speed ofthe liquid, and N is a natural number, and a liquid column resonance isexcited in the liquid column resonance-generating liquid chamber tothereby continuously eject the toner composition liquid from the tonerejection holes. Note that a ratio Le/L is preferably greater than 0.6.The frequency generated by the vibration generating unit 20 ispreferably a high frequency vibration of 300 kHz or higher. With this, aliquid column resonance is excited in the liquid columnresonance-generating liquid chamber 18, and thereby the liquid can beejected from the ejection holes 19.

A drive signal from a vibration generating unit excites the vibrationgenerating unit 20 by pulse groups which is primarily composed of aliquid column resonance oscillation frequency depending on the length ofthe liquid column resonance-generating liquid chamber 18 in thelongitudinal direction thereof. With this, ejection of liquid dropletscan be controlled.

Further, the pulse group, as illustrated in FIG. 10. is divided intothree pulse parts of a preparatory pressure generating pulse part (awaveform during a period of (a) in FIG. 10), a drive main pulse part (awaveform during a period of (b) in FIG. 10), and a residual vibrationundoing pulse part (a waveform during a period of (c) in FIG. 10). Thepreparatory pressure generating pulse part is present at the leadingedge of the pulse groups and excites the liquid in the liquid columnresonance-generating liquid chamber to allow the liquid to remain in astate of not flying the liquid droplets. The drive main pulse part is anapplication pulse following the preparatory generating pulse part andejects the liquid from the ejection hole. The residual vibration undoingpulse part is an application pulse immediately after the drive mainpulse part and includes a frequency component having a phase opposite tothat of a main frequency component of the drive main pulse part. Withthis, the ejection quantity of liquid droplets and the ejection timingcan be accurately controlled.

A liquid droplet ejection head 11 illustrated in FIG. 1 includes aliquid column resonance-generating liquid chamber 18 and a vibrationgenerating unit 20. In the liquid column resonance-generating liquidchamber 18, ejection holes 19 are formed at a part of a plateconstituting the liquid chamber 18. Further, a vibration generating unit20 for applying a vibration to a liquid in the liquid columnresonance-generating liquid chamber 18 is provided. A vibration isapplied inside the liquid column resonance-generating liquid chamber 18by the vibration generating unit 20 so that a standing wave throughliquid column resonance is formed in the liquid columnresonance-generating liquid chamber 18 to thereby eject the liquid fromthe ejection holes 19. With this, the resonance frequency can bedesirably set, and extremely fine liquid droplets can be produced.

Further, the ejection holes 19 are formed in a region (in a memberconstituting the liquid column resonance-generating liquid chamber 18)corresponding to an antinode of the standing wave through the liquidcolumn resonance formed in the liquid column resonance-generating liquidchamber 18. The region corresponding to an antinode of the standing wavethrough the liquid column resonance is a region where the pressurebecomes a maximum, thereby stable ejection of liquid droplets can beachieved.

Further, by using the liquid droplet ejecting method with the inkjetrecording apparatus, or including the liquid droplet ejection apparatus,ink droplets can be ejected with a lower voltage and a high-densityrecording can be achieved.

<Fine Particle Production Method, Fine Particle Production Apparatus,and Toner>

FIG. 13 is a cross-sectional diagram illustrating the overallconfiguration of a toner production apparatus according to oneembodiment of the present invention. FIG. 14 is a cross-sectionaldiagram illustrating the configuration of the liquid droplet ejectionhead in the liquid droplet forming unit (liquid droplet ejectionapparatus) in FIG. 13. FIG. 15 is an A-A′ line cross-sectional diagramillustrating the configuration of the liquid droplet forming unit inFIG. 13.

A toner production apparatus 1 according to the present embodimentillustrated in FIG. 13 mainly include a liquid droplet forming unit 10and a dry-collection unit 30. The liquid droplet forming unit 10includes a plurality of arrays of liquid droplet ejection heads 11 eachof which is a liquid droplet forming unit configured to eject a tonercomposition liquid in a liquid column resonance-generating liquidchamber which is a liquid chamber having a liquid jetting area incommunication with exterior portions through ejection holes, and inwhich a liquid column resonance standing wave is generated under theafter-mentioned conditions, as liquid droplets from the ejection holes.On both sides of each of the liquid droplet ejection heads 11, an airstream path 12 is provided, through which an air stream generated by anunillustrated air stream generating unit passes so that liquid dropletsof the toner composition liquid ejected from the liquid droplet ejectionheads 11 flows out to a dry-collection unit 30. Further, the liquiddroplet forming unit 10 includes a material housing container 13 tohouse a toner composition liquid 14, which is a toner material, and aliquid circulation pump 15 which feeds the toner composition liquid 14housed in the material housing container 13 to the after-mentionedliquid common feed path 17 in the liquid droplet ejection head 11 via aliquid feed path 16 and further pressure-feeds the toner compositionliquid 14 in the liquid feed path 16 so as to be returned to thematerial housing container 13 via a liquid return pipe 22. Furthermore,the liquid droplet ejection head 11 includes, as illustrated in FIG. 14,a liquid common feed path 17 and a liquid column resonance-generatingchamber 18. The liquid column resonance-generating chamber 18 isdesigned to communicate with the liquid common feed path 17 which isdisposed at one wall surface of wall surfaces provided at both ends ofthe liquid column resonance-generating chamber 18 in a longitudinaldirection thereof. In addition, the liquid column resonance-generatingchamber 18 includes ejection holes 19 which ejects liquid droplets 21 atone wall surface of wall surfaces connected to the wall surfacesprovided at the both ends, and a vibration generating unit 20 which isprovided at a wall surface facing the ejection holes 19 and isconfigured to generate a high frequency vibration for forming a liquidcolumn resonance standing wave. Note that an unillustratedhigh-frequency power source is connected to the vibration generatingunit 20.

The dry-collection unit 30 illustrated in FIG. 13 includes a chamber 31and a toner collection part 32. In the chamber 31, a large-size downwardair stream is formed. In the large-size downward air stream, an airstream generated by an unillustrated air stream-generating unit isunited with a downward air stream 33. Since the liquid droplets 21ejected from the liquid droplet ejection head 11 in the liquid dropletforming unit 10 is conveyed downward by not only gravity but also thedownward air stream 33, it is possible to prevent the liquid droplets 21ejected from decelerating by wind drag (air resistance). With thisconfiguration, when liquid droplets 21 are continuously ejected, it ispossible to prevent a liquid droplet 21 ejected in first (former liquiddroplet) from decelerating by air resistance and prevent a liquiddroplet 21 ejected afterward from catching up with the former liquiddroplet 21 to unite with the former liquid droplet 21 to be a liquiddroplet 21 having a large particle diameter, i.e., it is possible toprevent the liquid droplets 21 from having large particle diameters.Note that, as an air stream-generating unit, any of the followingmethods can be employed: a method in which an air blower is provided atan upstream portion to pressurize the inside of the chamber 31, and amethod in which the inside of the chamber is sucked from the tonercollection part 32 to thereby reduce the pressure. In the tonercollection part 32, a rotational air stream generating device (notillustrated) is provided, which generates a rotational air streamrotating around an axis in parallel with a perpendicular direction.Further, the toner collection part 32 includes a toner reservoir part 35which stores toner particles that have passed through a toner collectiontube 34 in communication with the chamber 31 and then dried andsolidified.

Next, a toner production process employed by the toner productionapparatus according to the present embodiment will be outlined.

The toner composition liquid 14 housed in the material housing container13 illustrated in FIG. 13 passes through the liquid feed path 16 by theliquid circulation pump 15 for circulating the toner composition liquid14, flows into the liquid common feed path 17 in a liquid dropletforming unit 10 illustrated in FIG. 15, and then fed to the liquidcolumn resonance-generating chamber 18 in the liquid droplet ejectionhead 11 illustrated in FIG. 14. Then, inside the liquid columnresonance-generating chamber 18 which is filled with the tonercomposition liquid 14, a pressure distribution is formed by a liquidcolumn resonance standing wave generated by the vibration generatingunit 20. The liquid droplets 21 are ejected from the ejection holes 19arranged in an area corresponding to an antinode of the standing wavethrough liquid column resonance, the antinode is a portion having alarge amplitude in the liquid column resonance standing wave and highpressure variations. The “area corresponding to an antinode of thestanding wave through liquid column resonance” means an area other thanthe node of the standing wave. Preferably, this area is an area havingsuch a sufficiently large amplitude that the liquid is ejected by achange in pressure (pressure variation) of the standing wave, and morepreferably, an area within a range of ±¼ wavelength from a positionwhere the amplitude of the pressure standing wave becomes a maximum (anode in a speed standing wave) toward a position where the amplitudebecomes a minimum (see FIG. 4). Even when a plurality of ejection holesare formed, it is possible to form substantially uniform liquid dropletsfrom the respective ejection holes, provided that the ejection holes areformed in the area corresponding to an antinode of the standing wave.Further, the liquid droplets can be efficiently ejected, and clogging ofejection holes hardly occurs. Note that the toner composition liquid 14passed thought the liquid common feed path 17 flows into a liquid returnpipe 22 and then returned to the material housing container 13. When theamount of the toner composition liquid 14 in the liquid columnresonance-generating chamber 18 is reduced by ejection of the liquiddroplets 21, a suction force effected by the liquid column resonancestanding wave in the liquid column resonance-generating chamber 18works, and the flow rate of the toner composition liquid 14 fed from theliquid common feed path 17 is increased, and thereby the liquid columnresonance-generating chamber 18 is refilled with the toner compositionliquid 14. Upon refilling the liquid column resonance-generating chamber18 with the toner composition liquid 14, the flow rate of the tonercomposition liquid 14 passing through the liquid common feed path 17 isrestored. In the liquid feed path 16 and liquid return pipe 22, the flowof the toner composition liquid 14 circulating in the apparatus isformed again. Meanwhile, as illustrated in FIG. 13, the liquid droplets21 ejected from the liquid droplet ejection head 11 in the liquiddroplet forming unit 10 are conveyed downward by not only gravity butalso the downward air stream 33 which is generated by an unillustratedair stream-generating unit and which passes through an air stream path12 to be formed. Next, a spiral air stream is formed along a cone-shapedinside surface constituting the toner collection part 32 by a rotationalair stream generated by an unillustrated rotational air streamgenerating device in the toner collection part 32 and the downward airstream 33, and toner particles flow on the spiral air stream and driedand solidified in a laminar state. The dried and solidified tonerparticles pass through a toner collection tube 34 to be housed in thetoner reservoir part 35.

Note that the liquid column resonance-generating liquid chamber 18 in aliquid droplet ejection head 11 is formed to joint a frame formed of amaterial having such high rigidity that does not adversely influenceupon the resonance frequency of the liquid, such as metal, ceramics, andsilicon. Further, as illustrated in FIG. 14, a length L between the wallsurfaces provided at both ends of the liquid column resonance-generatingliquid chamber 18 in a longitudinal direction thereof is determinedbased on the above-mentioned liquid column resonance principle. Further,a width W of the liquid column resonance-generating liquid chamber 18illustrated in FIG. 15 is preferably smaller than one-half the length Lof the liquid column resonance-generating liquid chamber 18 so as not togive extra frequencies to liquid column resonance. Furthermore, toremarkably increase the productivity, the liquid columnresonance-generating chamber 18 is preferably arranged in plurality withrespect to one unit of the liquid droplet forming unit 10. The range ofthe number of the liquid column resonance-generating chamber 18 to bearranged is not particularly limited. However, one liquid dropletforming unit provided with 100 units to 2,000 units of the liquid columnresonance-generating chamber 18 is most preferable because both theoperability and productivity can be simultaneously achieved. A flow pathfor liquid feeding is continuously jointed for each liquid columnresonance-generating liquid chamber, from the common feed path 17, and aplurality of the liquid column resonance-generating chambers 18 are incommunicate with the liquid common feed path 17.

The vibration generating unit 20 in the liquid droplet ejection head 11is not particularly limited, as long as it can drive at a givenfrequency. Such an aspect is desired in which a piezoelectric element islaminated to an elastic plate. The elastic plate constitutes part of thewall in the liquid column resonance-generating chamber so that thepiezoelectric element comes into contact with the liquid. Examples ofmaterial for the elastic plate include piezoelectric ceramics such aslead zirconate titanate (PZT). Generally, since such a material has asmall amount of displacement, in most cases, it is used in a laminateform. Besides, piezoelectric polymers such as polyvinylidene fluoride(PVDF), crystal, and single crystal such as LiNbO₃, LiTaO₃, KNbO₃ areexemplified. Furthermore, the vibration generating unit 20 is desirablydisposed so that it can be individually controlled for each liquidcolumn resonance chamber. In addition, the following configuration isdesired: one material selected from those described above in a blockshape is partially cut to fit the arrangement of the liquid columnresonance-generating chamber, and respective liquid columnresonance-generating chambers can be controlled individually, via anelastic plate.

Further, the aperture diameter of the ejection holes 19 is preferablywithin a range of 1 μm to 40 μm. When the aperture diameter is smallerthan 1 μm, liquid droplets to be formed are very small, and thus it maybe impossible to obtain a toner. In addition, when the toner containssolid fine particles of a pigment or the like as a toner component,there is a concern that clogging often occurs in the ejection holes 19,causing a reduction of productivity. When the aperture diameter isgreater than 40 μm, the diameter of liquid droplets formed is increased.When the toner particles having a desired particle diameter of from 3 μmto 6 μm by drying and solidifying the liquid droplets, it is sometimesnecessary to dilute the toner composition to a very dilute liquid withan organic solvent, and inconveniently, a large amount of dry energy isneeded to obtain a certain amount of toner. As can be seen from FIG. 15,it is preferable to provide the ejection holes 19 in the liquid columnresonance-generating chamber 18 in its width direction because a numberof apertures of the ejections holes can be arranged therein, and thusthe productivity is increased.

Using the principle of the liquid column resonance phenomenon addescribed above, a liquid column resonance standing wave is formed inthe liquid column resonance-generating chamber 18 illustrated in FIG.14, and liquid droplets are continuously ejected in the ejection holes19 arranged at part of the liquid column resonance-generating chamber18. Note that when the ejection holes 19 are arranged at a positionwhere the pressure of the standing wave varies at most, it is preferablein that the ejection efficiency is increased and driving with lowvoltage can be achieved. In addition, one ejection hole (the ejectionhole 19) may be formed in the liquid column resonance-generating chamber18, however, from the viewpoint of productivity, it is preferable that aplurality of the ejection holes 19 be formed. Specifically, the numberof ejection holes is preferably 2 to 100. When the number of ejectionholes exceeds 100, and when desired toner liquid droplets are to beformed from 100 holes of the ejection holes 19, there is a need to set avoltage applied to the vibration generating unit 20 high, and thebehavior of the piezoelectric element serving as the vibrationgenerating unit 20 becomes unstable. In addition, in the case where aplurality of the ejection holes are formed, a pitch between the tonerejection holes is preferably 20 μm or greater and equal to or smallerthan the length of the liquid column resonance-generating liquidchamber. When the pitch is greater than 20 μm, there is a highprobability that liquid droplets discharged from adjacent ejection holescollide with each other to be a large-size droplet, leading todegradation in particle size distribution of the toner.

Next, one example of a configuration where liquid droplets are actuallyejected by the liquid column resonance phenomenon will be described.This example is a case where in FIG. 14, the length L between both endsof the liquid column resonance-generating chamber 18 in the longitudinaldirection thereof is 1.85 mm, and a resonance mode: N=2. Toner ejectionholes are arranged at a position corresponding to an antinode of apressure standing wave based on the resonance mode of N=2, and theappearance of the ejection holes (a first ejection hole to a fourthejection hole), from which liquid droplets were ejected with a drivefrequency of a sine wave at 340 kHz, was photographed by lasershadowgraphy is illustrated in FIG. 16. As can be seen from FIG. 16,ejection of liquid droplets with extremely uniform in diameter andsubstantially uniform speed was achieved. FIG. 17 is a characteristicgraph illustrating characteristics between a drive frequency and aliquid droplet ejection speed, when driving was performed with anamplitude sine wave having the same amplitude as a drive frequency of290 kHz to 395 kHz. As can be seen from FIG. 17, the ejection speed ofliquid droplets from each ejection hole is equalized in the vicinity ofdrive frequency of 340 kHz, in the first ejection hole to the fourthejection hole, and a maximum ejection speed is achieved. From thischaracteristic result, it is understood that uniform ejection isachieved at a position corresponding to an antinode of the liquid columnresonance standing wave with a drive frequency of 340 kHz, which is asecond mode of liquid column resonance frequency. In addition, from thecharacteristic result in FIG. 17, it is understood that frequencycharacteristics of liquid column resonance standing waves that liquiddroplets are not ejected during a period between a liquid dropletejection speed peak at a drive frequency of 130 kHz (first mode) and aliquid droplet ejection speed peak at a drive frequency of 340 kHz(second mode) occurs in the liquid column resonance-generating liquidchamber.

FIG. 18 is a characteristic graph illustrating a relationship between avoltage applied and an ejection speed in each ejection hole. FIG. 19 isa characteristic graph illustrating a relationship between a voltageapplied and a diameter of a liquid droplet. As can be seed from thesefigures, both the ejection speed and diameter of liquid droplets tend tomonotonously increase relative to an increase in voltage. Since theejection speed and the diameter of liquid droplets depend on the voltageapplied, the diameter of liquid droplets can be adjusted according tothe desired ejection speed or the desired diameter of toner particlescan be controlled by adjusting a voltage applied to the piezoelectricelement.

Hereinbelow, examples (Examples 15 to 27) relating to a numericalaperture, pattern and arrangement of ejection holes of a liquid ejectionhead in a toner production apparatus according to the present embodimentwill be described. Note that the present invention is not limited to thedisclosed Examples. By actually making a search for ejection frequenciesin the following Examples 15 to 27, the resonance frequency can beknown. A toner composition liquid was ejected under different conditionsto obtain toner base particles, followed by addition of externaladditives, to thereby obtain a toner. The evaluation results of thetoner are also described.

A toner relating to the present invention will be described as anexample of fine particles.

The toner according to the present invention is a toner produced by atoner production method to which the present invention is applied, as inthe case of the toner production apparatus according to the presentembodiment described above. With this, a toner having a mono-dispersedparticle size distribution can be obtained.

Specifically, the particle size distribution (weight average particlediameter/number average particle diameter) of the toner is preferablywithin a range of 1.00 to 1.15, and more preferably within a range of1.00 to 1.05. The weight average particle diameter is preferably withina range of 1 μm to 20 μm, and more preferably within a range of 3 μm to10 μm.

Next, toner materials usable in the present invention will be described.Firstly, as disclosed above, a toner composition liquid dispersed ordissolved in a solvent will be described.

As toner materials, the same ones as used in a conventionalelectrophotographic toner can be used. In other words, a toner binder(e.g., a styrene acryl-based resin, polyester-based resin, polyol-basedresin, and epoxy-based resin) is dissolved in each individual organicsolvent, a colorant is dispersed, a releasing agent is dispersed ordissolved in the organic solvent, and the resulting dispersion orsolution is dried and solidified as microscopic liquid droplets by thetoner production method to thereby make it possible to produce intendedtoner particles.

[Toner Material]

The toner materials include at least a resin, a colorant and wax, andwhen necessary, include a charge controlling agent, additives and othercomponents.

[Resin]

As the resin, at least a binder resin is exemplified.

The binder resin is not particularly limited, and may be suitablyselected from commonly used resins for use. Examples of the binder resininclude vinyl polymers such as a styrene-based monomer, an acrylic-basedmonomer and a methacrylic-based monomer, copolymers of at least one ofthe monomers, polyester-based polymers, polyol resins, phenol resins,silicone resins, polyurethane resins, polyamide resins, furan resins,epoxy resins, xylene resins, terpene resins, coumaroneindene resins,polycarbonate resins, and petroleum-based resins.

Examples of the styrene-based monomer include styrenes such as styrene,o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene,p-ethylstyrene, 2,4-dimethylstyrene, p-n-amylstyrene,p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene,p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene,p-methoxystyrene, p-chlorostyrene, 3,4-dichlorostyrene, m-nitrostyrene,o-nitrostyrene, and p-nitrostyrene or derivatives thereof.

Examples of the acrylic-based monomer include an acrylic acid or acrylicacids such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butylacrylate, isobutyl acrylate, n-octyl acrylate, n-dodecyl acrylate,2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, andphenyl acrylate or esters thereof.

Examples of the methacrylic-based monomer include a methacrylic acid ormethacrylic acids such as methyl methacrylate, ethyl methacrylate,propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate,n-octyl methacrylate, n-dodecyl methacrylate, 2-ethylhexyl methacrylate,stearyl methacrylate, phenyl methacrylate, dimethylaminoethylmethacrylate, and diethylaminoethyl methacrylate or esters thereof.

As other monomers forming the vinyl polymer or copolymer, the followingmonomers (1) to (18) are exemplified. Specific examples thereof are (1)monoolefins (e.g., ethylene, propylene, butylene, and isobutylene); (2)polyenes (e.g., butadiene, and isoprene); (3) halogenated vinyls (e.g.,vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride);(4) vinyl esters (e.g., vinyl acetate, vinyl propionate, and vinylbenzoate); (5) vinyl ethers (e.g., vinyl methyl ether, vinyl ethylether, and vinyl isobutyl ether); (6) vinyl ketones (e.g., vinyl methylketone, vinyl hexyl ketone, and methyl isopropenyl ketone); (7) N-vinylcompounds (e.g., N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, andN-vinyl pyrolidone); (8) vinyl naphthalines; (9) acrylic acid ormethacrylic acid derivatives (e.g., acrylonitrile, methacrylonitrile,and acrylamide); (10) unsaturated dibasic acids (e.g., maleic acid,citraconic acid, itaconic acid, alkenylsuccinic acid, fumaric acid, andmesaconic acid); (11) unsaturated dibasic anhydrides (e.g., maleicanhydride, citraconic anhydride, itaconic anhydride, and alkenylsuccinicanhydride); (12) unsaturated dibasic acid monoesters (e.g., maleic acidmonomethyl ester, maleic acid monoethyl ester, maleic acid monobutylester, citraconic acid monomethyl ester, citraconic acid monoethylester, citraconic acid monobutyl ester, itaconic acid monomethyl ester,alkenylsuccinic acid monomethyl ester, fumaric acid monomethyl ester,and mesaconic acid monomethyl ester); (13) unsaturated dibasic esters(e.g., dimethyl maleate, and dimethyl fumarate); (14) α,β-unsaturatedacids (e.g., crotonic acid, and cinnamic acid); (15) α,β-unsaturatedanhydrides (e.g., crotonic anhydride, and cinnamic anhydride); (16)anhydrides between the α,β-unsaturated and a lower fatty acid, alkenylmalonic acid, alkenyl glutaric acid, alkenyl adipic acid, acidanhydrides thereof, and monomers having a carboxyl group such asmonoesters thereof; (17) acrylic acid or methacrylic acid hydroxy alkylesters (e.g., 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and2-hydroxypropyl methacrylate); and (18) monomers having a hydroxy group(e.g., 4-(1-hydroxy-1-methylbutyl)styrene, and4-(1-hydroxy-1-methylhexyl)styrene).

In a toner according to the present invention, the vinyl polymer as thebinder resin may have a structure crosslinked by a crosslinking agenthaving two or more vinyl groups. Examples of the crosslinking agent usedin this case, as aromatic divinyl compounds, include divinyl benzene,and divinyl naphthalene; as diacrylate compounds each linked by an alkylchain, include ethylene glycol diacrylate, 1,3-butylene glycoldiacrylate, 1,4-butanediol diacrylate, 1,5-pentane diol diacrylate,1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and compoundswhere acrylates of these compounds are replaced by methacrylates; and,as diacrylate compounds each linked by an alkyl chain containing anether bond, include diethylene glycol diacrylate, triethylene glycoldiacrylate, tetraethylene glycol diacrylate, polyethylene glycol #400diacrylate, polyethylene glycol #600 diacrylate, dipropylene glycoldiacrylate, and compounds where acrylates of these compounds arereplaced by methacrylates.

As the monomer forming the vinyl polymer or copolymer, there may be alsoexemplified diacrylate compounds and dimethacrylate compounds eachlinked by a chain containing an aromatic group and an ether bond. Aspolyester type diacrylates, for example, MANDA (product name, producedby Nippon Kayaku Co., Ltd.) is exemplified.

Examples of polyfunctional crosslinking agents include pentaerythritolacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate,tetramethylolmethane tetraacrylate, oligoester acrylate, compounds whereacrylates of these compounds are replaced by methacrylates, triallylcyanurate, and triallyl trimellitate.

These crosslinking agents are preferably used in an amount of 0.01 partsby mass to 10 parts by mass, more preferably in an amount of 0.03 partsby mass to 5 parts by mass relative to 100 parts by mass of the othermonomer components. Among these crosslinkable monomers, aromatic divinylcompounds (particularly, divinyl benzene), and diacrylate compoundslinked by a linking chain containing an aromatic group and one etherbond are preferably exemplified. Among these monomers, preferred is acombination of monomers so as to be a styrene-based polymer or a styreneacrylic-based copolymer.

Examples of a polymerization initiator for use in production of thevinyl polymer or vinyl copolymer of the present invention include2,2′-Azobisisobutyronitrile,2,2′-Azobis(4-methoxy-2,4-dimethylvaleronitrile),2,2′-Azobis(2,4-dimethylvaleronitrile),2,2′-Azobis(2-methylbutyronitrile), dimethyl-2,2′-azobisisobutylate,1,1′-azobis(1-cyclohexanecarbonitrile),2-(carbamoylazo)-isobutyronitrile, 2,2′-Azobis(2,4,4-trimethylpentane),2-phenylazo-2′,4′-dimethyl-4′-methoxyvaleronitrile,2,2′-Azobis(2-methylpropane), ketone peroxides (e.g., methylethylketoneperoxide, acetylacetone peroxide, and cyclohexanone peroxide),2,2-Bis(tert-butylperoxy)butane, tert-butyl hydroperoxide, cumenehydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-tert-butylperoxide, tert-butylcumyl peroxide, di-cumyl peroxide,α-(tert-buthylperoxy)isopropylbenzene, isobutyl peroxide, octanoylperoxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoylperoxide, benzoyl peroxide, m-tolyl peroxide, di-isopropylperoxydicarbonate, di-2-ethylhexylperoxy dicarbonate, di-n-propylperoxydicarbonate, di-2-ethoxyethylperoxy carbonate, di-ethoxyisopropylperoxydicarbonate, di(3-methyl-3-methoxybutyl)peroxycarbonate,acetylcyclohexylsulfonyl peroxide, tert-butylperoxy acetate,tert-butylperoxyisobutylate, tert-butylperoxy-2-ethylhexylate,tert-butylperoxylaurate, tert-butyl-oxybenzoate,tert-butylperoxyisopropyl carbonate, di-tert-butylperoxy isophthalate,tert-butylperoxyallyl carbonate, isoamylperoxy-2-ethylhexanoate,di-tert-butylperoxyhexahydro phthalate, and tert-butylperoxy azelate.

When the binder resin is a styrene-acrylic-based resin, it ispreferable, from the standpoint of fixability, offset resistance andstorage stability, for the resin to have a molecular weight distributionby way of GPC, which is soluble in a tetrahydrofuran (THF)(i.e.,tetrahydrofuran (THF)-soluble resin fraction), wherein at least one peakis present within a region of a molecular weight of 3,000 to 50,000 (bynumber average molecular weight conversion), and at least one peak ispresent within a region of a molecular weight of 100,000 or more. Inaddition, as the THF-soluble resin fraction), a binder resin containing50% to 90% of a resin component having a molecular weight of 100,000 orless is preferable; a binder resin having a main peak within a region ofa molecular weight of 5,000 to 30,000 is more preferable; and a binderresin having a main peak in a region of a molecular weight of 5,000 to20,000 is most preferable.

As an acid value when the binder resin a vinyl polymer, such as astyrene-acrylic-based resin, it is preferable to fall into a range of0.1 mg KOH/g to 100 mg KOH/g, with a range of 0.1 mg KOH/g to 70 mgKOH/g being more preferable thereupon, and a range of 0.1 mg KOH/g to 50mg KOH/g being most preferable thereupon.

As a monomer constituting the polyester-based polymer, the following areexemplified.

There may be exemplified, as a dihydric alcohol component, ethyleneglycol, propylene glycol, 1,3-butane diol, 1,4-butane diol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentane diol,1,6-hexane diol, neopentyl glycol, 2-ethyl-1,3-hexane diol, hydrogenatedbisphenol A, or such as a diol that is obtained by compounding a cyclicether, such as ethylene oxide or propylene oxide with hydrogenatedbisphenol A or bisphenol A.

It is preferable to combine the dihydric alcohol with a trihydric orhigher polyhydric alcohol in order to cause the polyester resin to forma cross linkage.

Examples of the trihydric or higher polyhydric alcohol include sorbitol,1,2,3,6-hexane tetrol, 1,4-sorbitan, pentaerythritol, an instancethereof being dipentaerythritol or tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropane triol,2-methyl-1,2,4-butane triol, trimethylol ethane, trimethylol propane, or1,3,5-trihydroxy benzene.

Examples of an acid component forming the polyester-based polymerinclude a benzene dicarbonate such as phthalic acid, isophthalic acid,or terephthalic acid, as well as the anhydrides thereof, an alkyldicarbonate such as succinic acid, adipic acid, sebacic acid, or azelaicacid, as well as the anhydrides thereof, an unsaturated dibasic acid,such as maleic acid, citraconic acid, itaconic acid, alkenyl succinicacid, fumaric acid, or mesaconic acid, as well as an unsaturated dibasicanhydride, such as maleic anhydride, citraconic anhydride, itaconicanhydride, or alkenyl succinic anhydride. Examples of trihydric orhigher polyhydric carbonic acid component include trimellitic acid,pyromellitic acid, 1,2,4-benzene tricarbonate, 1,2,5-benzenetricarbonate, 2,5,7-naphthalene tricarbonate, 1,2,4-naphthalenetricarbonate, 1,2,4-butane tricarbonate, 1,2,5-hexane tricarbonate,1,3-dicarboxy-2-methyl-2-methylene carboxy propane, tetra(methylenecarboxy)methane, 1,2,7,8-octane tetracarbonate, or Empol trimer, inaddition to the anhydrides or partial lower alkyl esters thereof.

When the binding resin is the polyester-based resin, it is preferable,from the standpoint of fixability, offset resistance and storagestability, for the resin to have a molecular weight distribution by wayof GPC, which is soluble in a tetrahydrofuran (THF) (i.e.,tetrahydrofuran (THF)-soluble resin component), wherein at least onepeak is present within a region of a molecular weight of 3,000 to50,000. In addition, as the THF-soluble resin fraction), a binder resincontaining 60% to 100% of a resin component having a molecular weight of100,000 or less is preferable; a binder resin having at least one peakwithin a region of a molecular weight of 5,000 to 20,000 is morepreferable.

As an acid value when the binder resin is a polyester resin, it ispreferable to fall into a range of 0.1 mg KOH/g to 100 mg KOH/g, with arange of 0.1 mg KOH/g to 70 mg KOH/g being more preferable thereupon,and a range of 0.1 mg KOH/g to 50 mg KOH/g being most preferablethereupon.

In the present invention, the molecular weight distribution of thebinder resin is measured by gel permeation chromatography (GPC) whereinthe THF is the solvent.

As the binder resin usable in the present invention, it is also possibleto use, from at least one of the vinyl polymer component and thepolyester-based resin component, a resin containing a monomer componentcapable of reacting with both of the resin component. Examples of themonomer which constitutes the polyester-based resin component and isreactive with a vinyl polymer include an unsaturated dicarboxylic acid,such as phthalic acid, maleic acid citraconic acid, and itaconic acid,as well as the anhydrides thereof. Examples of the monomer whichconstitutes the vinyl polymer component include those having a carboxylgroup or a hydroxy group, as well as an acrylic acid or methacrylamideacid ester.

In addition, when a polyester polymer and a vinyl polymer is combinedwith another binding resin, it is preferable for the acid value of thebinder resin overall to fall into a range of 0.1 mg KOH/g to 50 mgKOH/g, and it is preferable to use these binder resins in an amount of60% by mass or more.

According to the present invention, the acid value of the binder resincomponent of the toner composition material is derived by a method thatis described hereinafter. The basic operation thereof is performed inaccordance with JIS K-0070.

(1) Either prepare the material to be examined by either removing anadditive other than the binder resin, i.e., the polymer component, orobtain the acid value and a weight by component of the component otherthan the binder resin and the cross linked binder resin prior tocommencement. An amount of a powdered form of the material to beexamined of between 0.5 g and 2.0 g is precisely weighed, and a weightof the polymer component of the material thus weighed is treated as“Wg”. As an instance thereof, when measuring the acid value of thebinder resin from the toner, the acid value and the weight by componentof such as the coloring agent or the magnetic substance is measuredseparately from one another, and the acid value of the binder resinderived by taking the total of the acid values of the components of thebinder resin.(2) The material to be tested is placed in a 300 mL beaker, anddissolved by an addition into the beaker of 150 mL of a 4:1 (volumeratio) mixture of toluene/ethanol.(3) A KOH ethanol solvent at 0.1 mol/L is titrated using apotentiometric titration device.(4) The following Equation is used to calculate the acid value of thebinder resin, wherein a weight of the KOH solvent that is used in thepresent circumstance is treated as S (mL), the weight of the KOH solventthat is used in when another empty measurement is made simultaneously istreated as B (mL), and f is a KOH factor thereupon:

Acid value [mgKOH/g]=[(S−B)×f×5.61]/W

The binder resin for toner and the composition containing the binderresin preferably has a glass transition temperature (Tg) of 35° C. to80° C., and more preferably has a Tg of 40° C. to 75° C., from thestandpoint of storage stability of the resulting toner. When the Tg islower than 35° C., the toner is liable to degrade in a high-temperatureatmosphere, and the toner may be liable to cause offset when beingfixed. When the Tg is higher than 80° C., the fixability may degrade.

Examples of the magnetic substance usable in the present inventioninclude (1) a magnetic iron oxide, such as magnetite, maghemite, orferrite, as well as an iron oxide that includes another metallic oxide;(2) a metal such as iron, cobalt, or nickel, as well as an alloy ofthese metals with a metal such as aluminum, cobalt, copper, lead,magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calciummanganese, selenium, titanium, tungsten, or vanadium; and (3) mixturesthereof.

Specific examples of the magnetic substance include Fe₃O₄, γ-Fe₂O₃,ZnFe₂O₄, Y₃Fe₅O₁₂, CdFe₂O₄, Gd₃Fe₅O₁₂, CuFe₂O₄, PbFe₁₂O, NiFe₂O₄,NdFe₂O, BaFe₁₂O₁₉, MgFe₂O₄, MnFe₂O₄, LaFeO₃, iron powder, cobalt powder,and nickel powder. These may be used alone or in combination. Amongthese magnetic substances, a fine grain powder of iron oxide black orγ-diiron trioxide is particularly preferable, for example.

In addition, it is also possible to use a magnetic iron oxide whichcontains a different element, such as magnetite, maghemite, and ferrite,or a mixture thereof. Examples of the different element which is used inthe magnetic iron oxide include lithium, beryllium, boron, magnesium,aluminum, silicon, phosphorus, germanium, zirconium, tin, sulfur,calcium. scandium, titanium, vanadium, chromium, manganese, cobalt,nickel, copper, zinc, and gallium. As a preferable different element tobe used in the magnetic iron oxide, it is selected from among magnesium,aluminum, silicon, phosphorus, and zirconium. The different element maybe incorporated into an iron oxide crystal lattice, to be incorporatedinto the iron oxide as an oxide, or to be present upon a surface eitheras an oxide or a hydroxide. It is preferable for the different elementto be used in the magnetic iron oxide to be contained as the oxide.

It is possible to incorporate the different element to be used in themagnetic iron oxide into a particle by mixing a halogen of eachrespective different element when producing the magnetic substance, andadjusting a pH thereupon. In addition, it is possible to cause thedifferent element to precipitate upon the surface of the particle, byeither adjusting the pH after the production of the magnetic particle,or by adding a halogen of each respective element and adjusting the pHthereafter.

The use amount of the magnetic substance is preferably 10 parts by massto 200 parts by mass, and more preferably 20 parts by mass to 150 partsby mass, relative to 100 parts by mass of the binder resin. The numberaverage particle diameter of the magnetic substance is preferably 0.1 μmto 2 μm, and more preferably 0.1 μm to 0.5 μm. It is possible to derivethe number-average particle diameter of the magnetic substances by usinga digitizer etc. to measure an enlarged photograph that is captured witha transmission electron microscope.

In addition, as a magnetism property of the magnetic substance, it wouldbe preferable for the magnetism characteristic to fall into a coerciveforce range of 20 oersted to 150 oersted, a saturation magnetizationrange of 50 emu/g to 200 emu/g, and a residual magnetization range of 2emu/g to 20 emu/g, for each of a respective impression of 10K oersted.

The magnetic substance may also be used as a colorant.

[Colorant]

The colorant is not particularly limited and may be suitably selectedfrom among commonly used resins for use. Examples of the colorantinclude carbon black, nigrosine dye, iron black, naphthol yellow S,Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher,yellow lead, titanium yellow, Polyazo yellow, oil yellow, Hansa yellow(GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanentyellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake quinolineyellow Lake, Anthrazane yellow BGL, isoindolinone yellow, burnt ocher,cinnabar, lead vermillion, cadmium red, cadmium mercury red, antimonyvermillion, permanent red 4R, para red, parachlororthonitro aniline red,Lithol fast scarlet G, brilliant fast scarlet, brilliant carmine BS,permanent red (F2R, F4R, FRL, FRLL, F4RH), fast scarlet VD, Vulcan fastrubine B, brilliant scarlet G, Lithol rubine GX, permanent red F5R,brilliant carmine 6B, pigment scarlet 3B, Bordeaux 5B, toluidine maroon,permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon maroonlight, Bon maroon medium, eosin Lake, rhodamine Lake B, rhodamine LakeY, alizarin Lake, thioindigo red B, thioindigo maroon, oil red,Quinacridone red, pyrazolone red, Polyazo red, chromium vermillion,benzidine orange, perinone orange, oil orange, cobalt blue, ceruleanblue, alkali blue Lake, peacock blue Lake, Victoria blue Lake,non-metallic phthalocyanine blue, phthalocyanine blue, fast sky blue,indanthrene blue (RS, BC), indigo, lapis lazuli, ultramarine,anthraquinone blue, fast violet B, methyl violet Lake, cobalt purple,manganese purple, dioxane violet, anthraquinone violet, chromium green,zinc green, chromium oxide, viridian, emerald green, pigment green B,naphthol green B, green gold, acid green Lake, malachite green Lake,phthalocyanine green, anthraquinone green, titanium oxide, zinc pink, orLitho Bon, and mixtures thereof.

The amount of the colorant contained in the toner is preferably 1% bymass to 15% by mass, and more preferably 3% by mass to 10% by mass.

A colorant for use in a toner according to the present invention mayalso be used as a masterbatch which is compounded with the resin. As aninstance of the binder resin that is used in the production of themasterbatch, or that is mixed and kneaded with the masterbatch, inaddition to both the modified and unmodified polyester resins describedabove, there may be exemplified styrene, such as polystyrene, polyp-chlorostyrene, or polyvinyl toluene, as well as a polymer of asubstitution product of these styrenes; a styrene-based copolymer suchas styrene-p-chlorostyrene copolymer, styrene-propylene copolymer,styrene-vinyl toluene copolymer, styrene-vinyl naphthalene copolymer,styrene methylacrylate copolymer, styrene-ethylacrylate copolymer,styrene-butylacrylate copolymer, styrene-octylacrylate copolymer,styrene-methylmethacrylate copolymer, styrene-ethylmethacrylatecopolymer, styrene-butylmethacrylate copolymer,styrene-α-methylchlormethacrylate copolymer, styrene-acrylonitrilecopolymer, styrene-vinyl methylketone copolymer, styrene-butadienecopolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indenecopolymer, styrene-maleic acid copolymer, and styrene-maleic acid estercopolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinylchloride, polyvinyl acetate, polyethylene, polypropylene, polyester,epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinylbutyral, polyacrylate resin, rosin, modified rosin, terpene resin,aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin,paraffin chloride, and paraffin wax. These may be used alone or incombination.

It is possible to obtain the master batch by imparting a strong shearingforce to the resin and the colorant for the master batch, therebycompounding and mixing the resin and the colorant. In such acircumstance, it is possible to employ an organic solvent in order toincrease an interaction between the colorant and the resin. In addition,a so-called flashing method, wherein a water-based paste, which includesthe colorant in water, is compounded and mixed with the resin and theorganic solvent, the colorant is caused to transition to the resin sideof the mixture, and the water component and the organic solventcomponent are removed, is ideal, owing to the fact that a wet cake ofthe colorant may be employed as is, without needing to be desiccated. Astrong shearing dispersal apparatus, such as a triple roll mill, wouldbe ideal for the compounding and mixing of the colorant, the resin, andthe organic solvent.

The use amount of the masterbatch is preferably 0.1 parts by mass to 20parts by mass relative to 100 parts by mass of the binder resin.

In addition, it is preferable for the resin of the master batch to havean acid value of 30 mg KOH/g or lower, an amine value that falls into arange of 1 to 100, and to be used with the colorant dispersed thereupon,with an acid value of 20 mg KOH/g or lower, an amine value that fallsinto a range of 10 to 50, and to be used with the colorant dispersedthereupon being more preferable. When the acid value is higher than 30mg KOH/g, the chargeability of the masterbatch degrades under a highmoisture condition, and thus, the pigment dispersibility to themasterbatch may be insufficient. In addition, the pigment dispersibilityto the masterbatch may also be insufficient when the amine value is lessthan 1 or the amine value is greater than 100. Note that it is possibleto measure the acid value by a method that is specified in JIS K-0070,and that it is possible to measure the amine value by a method describedin JIS K-7237.

In addition, from the standpoint of the pigment dispersibility, thedispersant preferably has a strong compatibility with the binder resin,and as a concrete commercially available dispersant having the strongcompatibility with the binder resin, there may be exemplified AJISPERPB821 and AJISPER PB822, produced by Ajinomoto Fine-Techno Co., Inc.,DISPERBYK-2001, produced by Byk Additives & Instruments, and EFKA-4010,produced by EFKA Additives (a member of Ciba Specialty Chemicals).

It is preferable for the dispersant to add into the toner at aproportion that falls into a range of 0.1% by mass to 10% by massrelative to the colorant. When the proportion of the combination of thedispersant with respect to the colorant is less than 0.1% by mass, thepigment dispersibility may be insufficient, whereas, when the proportionof the combination of the dispersant with respect to the colorant isgreater than 10% by mass, the chargeability may degrade under a highmoisture condition.

The weight average molecular weight of the dispersant preferably fallsinto a range of 500 to 100,000, a main peak, i.e., a local maximum, ofthe molecular weight, with respect to a styrene conversion mass asdetermined by the gel permeation chromatography, and it is morepreferable, from the standpoint of the pigment dispersibility, theweight-average molecular weight of the dispersant to fall into a rangeof 3,000 and 100,000, with a range of 5,000 to 50,000 being particularlypreferable, and a range of 5,000 to 30,000 being most preferable. Whenthe molecular weight is less than 500, the polarity may increase, andthe colorant dispersibility may degrade, whereas, when the molecularweight is greater than 100,000, the affinity of the dispersant with thesolvent may increase, and the colorant dispersibility may degrade.

The addition amount of the dispersant is preferably 1 part by mass to200 parts by mass, and more preferably 5 parts by mass to 80 parts bymass, relative to 100 parts by mass of the colorant. When the additionamount of the dispersant is less than 1 part by mass, the dispersibilitymay decrease, whereas, when it is more than 200 parts by mass, thechargeability made degrade.

<Wax>

The toner composition liquid for use in the present invention contains awax together with the binder resin and the colorant.

The wax is not particularly limited and may be suitably selected fromamong commonly used ones for use. Examples of the wax include analiphatic hydrocarbon wax, such as low molecular weight polyethylene,low molecular weight polypropylene, a polyolefin wax, microcrystallinewax, paraffin wax, or Sasol wax, an oxide of an aliphatic hydrocarbonwax, such as polyethylene oxide wax, or a block copolymer of thesewaxes, a plant derived wax such as candelilla wax, carnauba wax,vegetable wax, or jojoba wax, an animal product wax such as beeswax,lanolin, or spermaceti, a mineral based wax such as Ozokerite, ceresin,or petrolatum, or a type of wax that treats a fatty acid ester as aprimary component, such as montanic acid ester wax or castor wax. Inaddition, a partially or totally deoxidized fatty acid ester wax, suchas deoxidized carnauba wax may also be exemplified.

Furthermore, as the wax that is used together with the binder resin andthe colorant, there may also be exemplified a saturated linear chainfatty acid, such as palmitic acid, stearic acid, montanic acid, or alinear chain alkyl carbonate further containing a linear chain alkyl, anunsaturated fatty acid such as eleostearic acid or parinaric acid, asaturated alcohol such as stearyl alcohol, eicosyl alcohol, behenylalcohol, carnaubyl alcohol, seryl alcohol, melissyl alcohol, or a longchain alkyl alcohol, a polyvalent alcohol such as sorbitol, a fatty acidamide such as linoleate amide, olefiate acid amide, or laurate amide, asaturated fatty acid bisamide such as methylene biscapriate amide,ethylene-bis laurate amide, hexamethylene-bistearate, an unsaturatedfatty acid amide such as ethylene bisoleate amide, hexamethylenebisoleate amide, N,N′-dioleal adipate amide, or N,N′-dioleal sebacateamide, an aromatic bisamide such as m-xylene bistearate amide,N,N-distearyl isophthalate amide, a fatty acid metallic salt such ascalcium stearate, calcium laurate, zinc stearate, or magnesium stearate,a wax that is grafted by employing a vinyl monomer, such as styrene oracrylate upon a aliphatic hydrocarbon wax, a compound of a fatty acidand a partial ester polyvalent alcohol, such as behenic acidmonoglyceride, or a methyl ester compound, containing a hydroxyl group,that is obtained by adding a hydrogen to a vegetable derived oil or fat.

More preferred examples of the wax include a polyolefin that is formedby radical polymerization of an olefin under a high pressure, apolyolefin that is obtained when polymerizing a high molecular weightpolyolefin by refining a low molecular weight by-product of thepolymerizing of the high molecular weight polyolefin, a polyolefin thatis polymerized by employing a medium at low pressure, such as a Zieglermedium or a metallocene medium, a polyolefin that is polymerized byemploying a radiation, an electromagnetic wave, or a light, a lowmolecular weight polyolefin that is obtained by thermally cracking ahigh molecular weight polyolefin, paraffin wax, microcrystalline wax,Fischer-Tropsch wax, a synthetic hydrocarbon wax that is synthesized bysuch as Zintol method, Hydrocol method, or AG method, a synthetic waxthat treats a single carbon compound as a monomer, a hydrocarbon waxcontaining a functional group such as a hydroxide group or a carboxylgroup, a compound of a hydrocarbon wax with a hydrocarbon wax containinga functional group, or a modified wax, treating the waxes describedherein as a matrix, whereupon a vinyl monomer, such as styrene, maleicacid ester, acrylate, methacrylate, or maleic acid anhydride is grafted.

In addition, it is preferable for the waxes described herein to beemployed subsequent to employing a press sweat technique, a solventtechnique, a recrystallization technique, a vacuum distillationtechnique, a supercritical gas extraction technique, or a solutioncrystallization technique to sharpen the molecular weight distribution,as well as to remove a low molecular weight solid fatty acid, a lowmolecular weight solid alcohol, a low molecular weight solid compound,or another such impurity thereupon.

The melting point of the wax is preferably, in order to achieve abalance between fixability and offset resistance, 70° C. to 140° C., andmore preferably 70° C. to 120° C. When the melting point is lower than70° C., the blocking resistance may degrade, whereas, when it is higherthan 140° C., the offset resistance effect may be hardly exhibited.

In addition, combining two or more different types of wax will allowsimultaneously exhibiting a plasticizing effect and a release effect,which are effects of the wax. As an example of the type of wax havingthe plasticizing effect, there may be exemplified a wax having a lowmelting point, or a structure further having a branched or a polar groupwith respect to a molecular structure of the wax. As an example of thetype of wax having the plasticizing effect, there may be exemplified awax having a low melting point, or a structure further having a branchedor a polar group with respect to a molecular structure of the wax. As anto example of the type of wax having the release effect, there may beexemplified a wax having a high melting point, or, as a molecularstructure of the wax, a wax having a linear chain structure or anon-polar type wax which does not include a functional group. As a useexample of a combination wax, there may be exemplified a combinationwherein a difference between the melting points of two or more differentkinds of wax falls into a range of 10° C. to 100° C., or a combinationof polyolefin and a modified polyolefin that is grafted upon thepolyolefin.

When selecting the two types of wax, in a circumstance wherein the twotypes of wax contain a similar structure, the wax having a relativelylower melting point exhibits the plasticizing effect, whereas the waxhaving a relatively higher melting point exhibits the release effect. Insuch a circumstance, a division of the functions between the two typesof wax is exhibited in an effectual manner when the difference betweenthe melting points falls within a range of 10° C. to 100° C. When thedifference between the melting points is lower than 10° C., the effectof the division of the functions may not be exhibited, whereas when thedifference between the melting points is higher than 100° C., aperformance of an emphasis of the functions of the two types of wax byway of an interaction may be impeded. In such a circumstance, given thata trend toward an case in the effecting the division of the functions ispresent, at least one of the waxes preferably has a melting point of 70°C. to 120° C., with a range of 70° C. to 100° C. being more preferable.

Within the wax thus formed, a modified wax component having a branchingstructure or a functional group such as a polar group, thereby differingrelatively from the primary component of the compound wax exhibits theplasticizing effect, whereas the invariant, i.e., linear, wax componentthat has a linear chain structure or that is nonpolar, having nofunctional group, exhibits the release effect. As a preferable waxcombination, there may be exemplified a combination of a polyethylenehomopolymer or copolymer that treats ethylene as the primary componentof the homopolymer or copolymer with a polyolefin homopolymer orcopolymer that treats an olefin other than ethylene as the primarycomponent of the homopolymer or copolymer, a combination of a polyolefinand a grafted metamorphic polyolefin, a combination of an alcohol wax, afatty acid wax, or an ester wax with a hydrocarbon wax, a combination ofa Fischer-Tropsch wax or a polyolefin wax with a paraffin wax or amicrocrystalline wax, a combination of a Fischer-Tropsch wax with apolyolefin wax, a combination of a paraffin wax with a microcrystallinewax, or a combination of carnauba wax, candelilla wax, rice wax, ormontanic wax with a hydrocarbon wax.

Regardless of the combination that is chosen, it is easy to achieve abalance between the storage stability and the fixability of the toner,and thus, with respect to an endothermic peak that is observed with aDSC measurement of the toner, it is preferable for a maximum peaktemperature to be present within a region of 70° C. to 110° C., with aregion of 70° C. to 110° C. having the maximum peak temperature beingmore preferable.

The total amount of the waxes is preferably 0.2 parts by mass to 20parts by mass and more preferably 0.5 part by mass to 10 parts by massrelative to 100 parts by mass of the binder resin.

According to the present invention, the maximum peak temperature of theendothermic peak of the wax, which is measured with the DSC, is presumedto be the melting point of the wax.

As a DSC measurement instrument of the wax or the toner, it ispreferable to perform the measurement with a differential calorimetry inan intra-cooler power compensation type with high precision. A method ofthe measurement is performed in accordance with ASTM D3418-82. A DSCcurve that is employed according to the present invention is employed,after the temperature of the substance to be measured is caused toincrease and decrease through a single cycle, and a history takenthereupon, when the temperature of the substance is measured upon beingcaused to increase at a speed of 10° C./min.

<Flowability Improver>

It is also be permissible to add a flowability improver to the toneraccording to the present invention. The flowability improver improvesthe flowability of the toner, i.e., makes the toner more liquid, upon anapplication of the flowability improver to the surface of the toner.

As an example of the flowability improver, there may be exemplifiedcarbon black, a fluorine resin powder such as fluoride vinylidene finegrain powder or polytetrafluoroethylene fine grain powder, a fine grainpowder silica such as a wet process silica or a dry process silica, afine grain powder titanium oxide, a fine grain powder aluminum oxide, aprocessed silica, a processed titanium oxide, or a processed aluminumoxide, whereupon a surface processing of the silica, the titanium oxide,or the aluminum oxide, is carried out by way of a silane coupling agent,a titanium coupling agent, or a silicon oil. From among thesesubstances, the fine grain powder silica, the fine grain powder titaniumoxide, or the fine grain powder aluminum oxide would be preferable, andmoreover, the processed silica whereupon the surface processing of thesilica by way of the silane coupling agent or the silicon oil is furtherpreferable.

The particle diameter of the flowability improver preferably, as anaverage primary particle diameter falls into a range of 0.001 μm to 2μm, with a range of 0.002 μm to 0.2 μm being more preferable.

The fine particle powder silica is a fine particle body that isgenerated by way of a gaseous phase oxidation of a silicon halide, whichis referred to as dry process silica or a fumed silica.

As an instance of a commercially available silica fine powder that isgenerated by the gaseous phase oxidation of the silicon halide, theremay be exemplified AEROSIL, AEROSIL-130, AEROSIL-300, AEROSIL-380,AEROSIL-TT600, AEROSIL-MOX170, AEROSIL-MOX80, or AEROSIL-COK84, whichare products of Nippon Aerosil; Ca-O-SiL-M-5, Ca-O-SiL-MS-7,Ca-O-SiL-MS-75, Ca-O-SiL-HS-5, or Ca-O-SiL-EH-5, which are products ofCabot Corporation; WACKER HDK-N20 V15, WACKER HDK-N20E, WACKER HDK-T30,OR WACKER HDK-T40, which are products of Waeker-Chiemie GmbH; D-C FineSilica, a product of Dow Corning Toray Co., Ltd.; or FRANSOL, a productof Fransil Co., Ltd.

Furthermore, it would be more preferable still for the silica fine grainbody that is generated by the gaseous phase oxidation of the substancecontaining silicon halide to include a processed silica fine grain bodywhereupon a hydrophobicity process has been performed. With respect tothe processed silica fine grain body, it would be especially preferablethe silica fine grain body to be processed such that a degree of thehydrophobicity that is measured by a methanol titration test preferablydenotes a value that falls into a range of between 30% and 80%. Thehydrophobicity is applied by way of either a reaction with the silicafine grain body, or either a chemical or a physical process, with suchas an organic silicon compound that physically adsorbs the silica finegrain body. As a preferable method of the hydrophobicity, a method thatprocesses the silica fine grain body that is generated by the gaseousphase oxidation of the substance containing silicon halide with theorganic silicon compound would be desirable.

As the organic silicon compound, there may be exemplified hydroxypropyltrimethoxysilane, phenyl trimethoxysilane, n-hexadecyl trimethoxysilane,n-octadecyl trimethoxysilane, vinyl methoxysilane, vinyltriethoxysilane, vinyl triacetoxysilane, dimethyl vinyl chlorosilane,divinyl chlorosilane, γ-methacrylamide oxypropyl trimethoxysilane,hexamethyl disilane, trimethylsilane, trimethyl chlorosilane, dimethyldichlorosilane, methyl trichlorosilane, allyl dimethyl chlorosilane,allyl phenyl dichlorosilane, benzyl dimethyl chlorosilane, bromomethyldimethyl chlorosilane, α-chlorethyl trichlorosilane, β-chloroethyltrichlorosilane, chloromethyl dimethylchlorosilane, triorganosilylmercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethyl acetoxysilane, dimethylethoxysilane, trimethyl othoxysilane,trimethyl methoxysilane, methyl triethoxysilane, isobutyltrimethoxysilane, dimethyl dimethoxysilane, diphenyl diethoxysilane,hexamethyl disiloxane, 1,3-divinyl tetramethyl disiloxane, or1,3-diphenyl tetramethyl disiloxane, as well as a dimethyl polysiloxane,having between 2 and 12 siloxane units per molecule, and either zero orone hydroxyl group bonded to a silicon atom on a basis of a unit that islocated at an end of the molecule, respectively. Furthermore, there mayalso be exemplified silicon oil, such as dimethyl silicon oil. These maybe used alone or in combination.

As a number average diameter of the flowability improver, it ispreferable to fall into a range of 5 nm to 100 nm, with a range of 5 nmto 50 nm being more preferable.

It is preferable for a specific surface area by way of a nitrogenadsorption that is measured with a BET technique to have a specificsurface area that is 30 m²/g or greater, with a specific surface areathat falls into a range of 60 m²/g to 400 m²/g being more preferable. Itwould be preferable for the fine powder that is surface treated to be 20m²/g or greater, with a range of 40 m²/g to 300 m²/g being morepreferable.

The appropriate use amount of the fine powders described herein ispreferably 0.03 parts by mass to 8 parts by mass relative to 100 partsby mass of the toner particles.

As another additive, it would be possible to add such as the followingto the toner according to the present invention, as necessary for anobjective such as protecting the electrostatic latent image support bodyor the carrier, improving a cleaning characteristic of the toner,adjusting a thermal characteristic, an electrical characteristic, or aphysical characteristic of the toner, adjusting a resistance of thetoner, adjusting a softening point of the toner, or improving a degreeof the fixing of the toner: any type of metallic soap, a fluorinesurfactant, dioctyl phthalate, such as tin oxide, zinc oxide, carbonblack, or antimony oxide as an agent conferring the conductivity uponthe toner, or an inorganic fine powder such as titanium oxide, aluminumoxide, or alumina. It is permissible to make hydrophobic the inorganicfine grain bodies described herein as necessary. In addition, it wouldalso be possible to employ, in small quantities, as a developmentimprover, a lubricant such as polytetrafluoroethylene, zinc stearate, orpolyfluoride vinylidene, an abrasive such as cesium oxide, siliconcarbide, or strontium titanate, or a caking prevention agent, andfurthermore, white fine grain particles and black fine grain particleseach of which has a polarity that is opposite to the polarity of thetoner particles.

It is also preferable for the additives described herein to be treatedby any or all of a treatment agent, such as is described hereinafter, inorder to achieve an objective such as controlling the quantity of thecharge of the toner; a silicon varnish, each type of denatured siliconvarnish, a silicon oil, each type of denatured silicon oil, a silanecoupling agent, silane coupling agent having a functional group, oranother organic silicon compound.

When preparing the developer, it would be permissible to add and mixinto the developer, the inorganic fine grain particle such as thehydrophobic silica fine grain powder that is described herein, in orderto increase the liquidity, the shelf life, the quality of thedeveloping, and the transferability of the developer. Whereas it wouldbe possible to select and use a typical granular compounding device forcompounding an external application agent as appropriate, it would bepreferable to be able to apply a coat such as a jacket, and to be ableto adjust an internal temperature. When changing a history of a loadthat is applied upon the external application agent, it would bepermissible to apply the external application agent either during theprocess or gradually, it would also be permissible to change such as anumber of rotations, i.e., per minute, a speed of transition, a time, ora temperature of the compounding device, and it would further bepossible to commence by imparting a high load, and thereafter impartinga comparatively lower load, as well as a converse thereof. As a usablecompounding device, there may be exemplified a V-shaped compoundingdevice, a rocking mixer, a lading mixer, a Nautor mixer, or a HENSCHELMIXER.

The method of further adjusting a shape of the toner is not particularlylimited, and may be suitably selected in accordance with the intendeduse. Examples of the method include, after fusing, mixing, andpulverizing the toner material that is formed from the binding resin andthe coloring agent, a method that employs such as a hybridizer ormechano-fusion upon the powdered toner material to mechanically adjustthe shape of the toner, as well as, after dissolving and dispersing thetoner material within a solvent that is capable of dissolving the tonerbinder with the so-called spray desiccation method, a method thatobtains a spherical toner by employing a spray desiccation device toremove the solvent from the toner, or a method that forms the sphericaltoner by heating the toner within the water based medium.

As the external additive, inorganic fine particles are preferably used.Examples of the inorganic fine particles include silica, aluminum oxide,titanium oxide, barium titanate, magnesium titanate, calcium titanate,strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica,wollastonite, diatomite, chromium oxide, cerium oxide, red haematite,antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate,barium carbonate, calcium carbonate, and silicon nitride. The primaryparticle diameter of the inorganic fine particles is preferably 5 μm to2 μm, and more preferably 5 μm to 500 μm.

The specific surface area by way of the BET technique is preferably 20m²/g to 500 m²/g. It would be preferable for a usage proportion of theinorganic fine particles to fall within a range of 0.01% by mass to 5%by mass of the toner, with a range of 0.01% by mass to 2.0% by mass ofthe toner being more preferable.

Besides, there may also be exemplified, as an example of a high polymerfine grain particle, a polymer particle by way of a polycondensationthermosetting resin, such as a polystyrene, a methacrylamide ester, anacrylate ester copolymer, or a silicon, a benzoguanamine, or as nylon,which is obtained by a soap free emulsion polymerization, a suspensionpolymerization, or a dispersion polymerization.

It is possible to increase the hydrophobicity of the external additiveby way of such a surface treatment agent thereupon, allowing preventinga degradation of the external additive even under a condition of a highdegree of humidity. As an example of the surface treatment agent, asilane coupling agent, a silylate agent, a silane coupling agent havinga fluoride alkyl group, an organic titanate coupling agent, an aluminumcoupling agent, a silicon oil, and a modified silicon oil are preferablyexemplified.

The primary particle diameter of the inorganic fine particles ispreferably 5 μm to 2 μm, and more preferably 5 μm to 500 μm. Thespecific surface area by way of the BET technique is preferably 20 m²/gto 500 m²/g. It would be preferable for a usage proportion of theinorganic fine particles to fall within a range of 0.01% by mass to 5%by mass of the toner, with a range of 0.01% by mass to 2.0% by mass ofthe toner being more preferable.

As an example of a cleanability improver, in order to remove thedeveloper that remains on the latent electrostatic image bearing memberor a primary transfer medium after the transfer of the image, there maybe exemplified a fatty acid metallic salt such as zinc stearate, calciumstearate, or stearic acid, as well as a polymer fine grain particle thatis manufactured by way of the soap free emulsion polymerization, such asa polymethyl methacrylate fine grain particle or a polystyrene finegrain particle. A narrow comparative particle density distribution ofthe polymer fine particles, wherein a volume average particle diameterfalls into a range of 0.01 μm to 1 μm, is preferable.

Whereas it is possible for the development method according to thepresent invention to use all of the latent electrostatic image bearingmembers used in the conventional electrophotography technique, it isideal, as an example thereof, to use such as an organic latentelectrostatic image bearing member, an amorphous silica latentelectrostatic image bearing member, a selenium latent electrostaticimage bearing member, or a zinc oxide latent electrostatic image bearingmember.

According to the toner production method of the present embodimenthaving been described above, at a part of a liquid columnresonance-generating liquid chamber 18 into which the toner containingat least a resin is supplied, ejection holes 19 for ejecting a tonercomposition liquid 14 are formed. In addition, in a liquid columnresonance-generating liquid chamber 18, a vibration generating unit 20configured to apply a vibration to the toner composition liquid isprovided. When such a frequency that is suitable for resonanceconditions is applied, a standing wave through liquid column resonanceis formed in the liquid column resonance-generating liquid chamber 18.By an effect of the standing wave through the liquid column resonance, apressure distribution is formed in the liquid columnresonance-generating liquid chamber 18. Further, in the standing wavethrough the liquid column resonance generated in the liquid columnresonance-generating liquid chamber 18, there is a region of thepressure distribution in which a high pressure is generated, which iscalled “antinode”. By providing the ejection holes 19 in the region ofthe pressure distribution corresponding to the antinode, the tonercomposition 14 is continuously ejected from the ejection holes 19.Thereafter, the toner liquid droplets which have been formed into liquiddroplets are solidified, and thereby toner particles are produced. Aplurality of the ejection holes 19 are formed relative to at least oneregion serving as the antinode of a standing wave through the liquidcolumn resonance. Thereby, continuous ejection of toner liquid dropletscan be achieved, and a high productivity can be expected. In addition, aplurality of toner ejection holes are formed relative to at least oneregion serving as the antinode of a standing wave, and further, byproviding a plurality of toner ejection holes in one liquid columnresonance-generating liquid chamber, the productivity is furtherimproved.

The vibration generating unit is effected to vibrate using a drivewaveform primarily containing a frequency f which satisfies f=N×c/(4L)when a length of the liquid column resonance-generating liquid chamberin a longitudinal direction thereof is represented by L, a frequency ofa high frequency vibration generated by the vibration generating unit isrepresented by f, a speed of sound wave of the toner composition liquidis represented by c, and N is a natural number, and a liquid columnresonance is excited in the liquid column resonance-generating liquidchamber to thereby continuously eject the toner composition liquid fromthe toner ejection holes. Thereby, the toner composition liquid can becontinuously and stably ejected from the ejection holes.

Further, the vibration generating unit is effected to vibrate using adrive waveform primarily containing a frequency f which is determined byusing L and Le and which satisfies N×c/(4L)≦f≦N×c/(4Le) when Lrepresents a length of the liquid column resonance-generating liquidchamber in a longitudinal direction of the liquid columnresonance-generating liquid chamber, Le represents a distance betweenthe end of the liquid column resonance-generating liquid chamber on theliquid feed path side and a center part of the ejection hole nearest tothe end of the liquid column resonance-generating liquid chamber, crepresents a sound speed of the liquid, and N is a natural number, and aliquid column resonance is excited in the liquid columnresonance-generating liquid chamber to thereby continuously eject thetoner composition liquid from the toner ejection holes. Thereby, thetoner composition liquid can be continuously and stably ejected from theejection holes. Note that Le and L preferably satisfy the relationshipLe/L>0.6.

Furthermore, the vibration generating unit is effected to vibrate usinga drive waveform primarily containing a frequency f which is determinedby using L and Le and which satisfies N×c/(4L)≦f≦(N+1)×c/(4Le) when Lrepresents a length of the liquid column resonance-generating liquidchamber in a longitudinal direction thereof, Le represents a distancebetween the end of the liquid column resonance-generating liquid chamberon the liquid feed path side and a center part of the ejection holenearest to the end of the liquid column resonance-generating liquidchamber, c represents a sound speed of the liquid, and N is a naturalnumber, and a liquid column resonance is excited in the liquid columnresonance-generating liquid chamber to thereby continuously eject thetoner composition liquid from the toner ejection holes.

In ejection of liquid droplets by only a liquid droplet forming unit,the flow rate of toner liquid droplets lowers by a viscosity resistanceof air to the toner liquid droplets, and there was a concern that thetoner liquid droplets aggregates each other when continuously ejected.To solve the problem, a flow path in which a gas flows and which formsan air stream for conveying toner liquid droplets that have been formedby a liquid droplet forming unit, to a solidifying unit is provided nearthe toner ejection holes, a further high speed is imparted to theejected toner liquid droplets, and thereby the leading toner liquiddroplets are prevented from aggregates with following toner liquiddroplets. Thereby, a toner having a uniform particle diameter can bestably produced.

Further, as the ejection speed of toner liquid droplets by the flow rateof gas can be controlled, the initial ejection speed of toner liquiddroplets ejected by the liquid droplet forming unit is preferably lowerthan the speed of the gas. When controlling of the speed of toner liquiddroplets is achieved, a toner composition liquid can be stably andcontinuously ejected without causing aggregation of ejected toner liquiddroplets. In addition, an organic solvent is contained in the tonercomposition liquid. In the solidifying unit, the organic solventcontained in the toner composition liquid is removed therefrom, and thetoner composition liquid is solidified by drying toner liquid droplets.By inclusion of an organic solvent, the toner composition liquid is notfixed inside the inkjet head, and thereby the efficiency of tonerproduction is increased.

A toner production apparatus 1 according to the present invention ismainly equipped with a liquid droplet forming unit 10 and a solidifyingunit 30. The liquid droplet forming unit 10 is configured to eject atoner composition liquid containing at least a resin from ejection holes19 arranged at a part of a surface of a liquid columnresonance-generating liquid chamber 18 illustrated in FIG. 14, thesurface being connected to both ends of the liquid columnresonance-generating liquid chamber 18 in its longitudinal direction toform the toner composition liquid into liquid droplets. In the liquidcolumn resonance-generating liquid chamber, at a part of one wallsurface of walls provided at both ends of a flow path in thelongitudinal direction, a liquid feed path 16 is provided, into whichthe toner composition liquid is fed. The liquid columnresonance-generating liquid chamber is further provided with a vibrationgenerating unit 20 for applying a vibration to the toner compositionliquid. When a high-frequency vibration, which is generated by thevibration generating unit 20, is applied to the toner composition liquidfed into the liquid column resonance-generating liquid chamber, astanding wave is generated, which is derived from a liquid columnresonance (by a liquid column resonance phenomenon) as illustrated inFIGS. 2A to 2D, FIGS. 3A to 3C and FIG. 4, which is formed in accordancewith resonance conditions between the walls at the both ends in of theliquid column resonance-generating liquid chamber in the longitudinaldirection thereof. Note that the vibration frequency generated by thevibration generating unit is preferably a high frequency vibration of300 kHz or higher. By generation of the standing wave through liquidcolumn resonance inside the liquid column resonance-generating liquidchamber, a pressure distribution is formed in the liquid columnresonance-generating liquid chamber. By the effect of the pressuredistribution, toner ejection and liquid supply are continuouslyperformed. Then, the ejected toner liquid droplets are solidified by thesolidifying unit to thereby produce toner particles. With this,continuous ejection of toner liquid droplets can be achieved, and a highproductivity can be expected.

Note that the present invention is not limited to the embodimentsdescribed above. On the contrary, the present invention is intended tocover various modifications and equivalent arrangements included withinthe spirit and scope of the appended claims.

EXAMPLES

Hereinafter, the present invention will be described with reference toExamples, which, however, shall not be construed as limiting the scopeof the invention.

Hereinbelow, the present invention will be further described in detailwith reference to Examples.

Example 1

In Example 1, using a liquid droplet ejection head illustrated in FIG.1, a waveform illustrated in FIG. 4 was applied to a piezoelectricelement of the vibration generating unit to form liquid droplets. Notethat a waveform of a main pulse part formed in a sine waveformcorresponding to 300 kHz was formed once. The ejection hole was made bynickel electroforming with a pore diameter of 8 μm. A liquid columnresonance-generating liquid chamber and a liquid supply path were formedby laminating a stainless steel path plate, to which a nickel thin filmwas laminated as an elastic plate. The piezoelectric element wasdisposed the upper part of the liquid column resonance-generating liquidchamber. These members are fixed with a stainless steel-made frame, asillustrated in FIG. 1. A mixture prepared in which a cyan pigment (0.5parts by mass) was added to ethyl acetate (100 parts) and then apolyester resin for adjusting the viscosity was added thereto, and themixture was added to compound a liquid for use. The quantity of oneliquid droplet relative to a voltage applied to the piezoelectricelement is described. In the measurement of the quantity of liquiddroplet, liquid droplets were discharged with a waveform at 30 kHz, andthe drive was stopped when 1,000,000 droplets were ejected, followed bya change in weight of the silicone liquid, in which an average weightthereof was measured. Further, flying liquid droplets were observedthrough a microscope at a high magnification, and the diameter of theliquid droplets was measured. As a result, liquid droplets in the samequantity as in the weight measurement method ware obtained. As a result,the quantity of one droplet measured with a pulse voltage of 8 V wasfound to be 0.7 pl.

Example 2

In Example 2, the procedure of Example 1 was repeated except that thenumber of driving times of the waveform of the main pulse part waschanged to two times. Thereafter, the same measurement for quantity ofliquid droplet was performed. As a result, the quantity of one dropletmeasured with a pulse voltage of 8 V was found to be 1.2 pl.

Example 3

In Example 3, the procedure of Example 1 was repeated except that thenumber of driving times of the waveform of the main pulse part waschanged to three times. Thereafter, the same measurement for quantity ofliquid droplet was performed. As a result, in one driving, two liquiddroplets were formed, and the quantity of one droplet measured with apulse voltage of 8 V was found to be 1.8 pl. The quantity of liquiddroplets can be modulated by changing the number of pulses of the mainpulse part in this way.

Example 4

In Example 4, the procedure of Example 1 was repeated except that themain pulse was changed to a waveform corresponding to 610 kHz, and thenumber of pulses was changed to two times. Thereafter, the samemeasurement for quantity of liquid droplet was performed. As a result,the quantity of one droplet measured with a pulse voltage of 8 V wasfound to be 0.5 l.

FIG. 11 is a characteristic graph illustrating the voltage dependency ofthe volume of liquid droplets. The figures illustrate the resultobtained after a voltage employed was changed under the conditions ofExample 1. As compared with the examples basically employing Helmholtzfrequency, it is understood that in Example 1, microscopic liquiddroplets can be driven with a low voltage.

Example 5

FIGS. 20A and 20B are diagrams illustrating an example of a liquiddroplet ejection head. In FIG. 20A, as illustrated in Example 5, Example5 is one example of a standing wave in the case where two ejection holes19 are formed in a liquid column resonance-generating liquid chamber 11on a fixed end side thereof, and a reflection wall is provided on theside of a liquid feed path in the liquid column resonance-generatingliquid chamber 11. it can be considered that the standing wave is in aresonance mode of N=2 at both ends thereof. Note that the drivefrequency was set to 328 kHz. Example 5 illustrates the result ofdriving using a frequency with a peaked resonance.

Example 6

FIGS. 21A and 21B are diagrams illustrating another example of a liquiddroplet ejection head. Example 6 illustrated in the figure is oneexample of a standing wave in the case where ten ejection holes 19 areformed in a liquid column resonance-generating liquid chamber 11 on afixed end side thereof, and a reflection wall is provided on the side ofa liquid common feed path in the liquid column resonance-generatingliquid chamber 11. Note that the drive frequency was set to 377 kHz.Therefore, as compared with Example 5 illustrated in FIG. 20A, thisliquid droplet ejection head was configured to have a loosely fixed end.

Example 7

FIGS. 22A and 22B are diagrams illustrating still another example of aliquid droplet ejection head. Example 7 illustrated in the figure is oneexample of a standing wave in the case where 24 ejection holes 19 areformed in a liquid column resonance-generating liquid chamber 11 on afixed end side thereof, and a reflection wall is provided on the side ofa liquid common feed path in the liquid column resonance-generatingliquid chamber 11. Note that the drive frequency was set to 417 kHz.Therefore, as compared with Example 5 illustrated in FIG. 20, theleading end side which was regarded as a fixed end in the liquid columnresonance-generating liquid chamber 11, a standing wave in a resonancemode of N=3, which is close to a standing wave formed at an open end,was formed.

Example 8

FIGS. 23A and 23B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 8 illustrated in the figure isone example of a standing wave in the case where four ejection holes 19are formed in a liquid column resonance-generating liquid chamber 11 ona fixed end side thereof, and a reflection wall is provided on the sideof a liquid common feed path in the liquid column resonance-generatingliquid chamber 11. Note that the drive frequency was set to 344 kHz.Therefore, as compared with Example 5 illustrated in FIG. 20, thisliquid droplet ejection head had a relatively loosely fixed end underthe influence of apertures of the ejection holes, in which a standingwave in a resonance mode of N=2 was formed.

Example 9

FIGS. 24A and 24B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 9 illustrated in the figure isone example of a standing wave in the case where the numerical apertureof toner ejection holes 19 is locally increased, the ejection holes 19are present near the liquid common feed path side and has a closed endat the other side of the liquid droplet ejection head. Thus, a standingwave in a resonance mode of N=1, which is a standing wave formed withclosed both ends, was formed, and as compared to a pressure distributionin a region provided with the toner ejection holes arranged near theliquid common feed path side, a pressure distribution in a regionprovided with the toner ejection holes arranged near the fixed end sidewas formed flat. Note that the drive frequency was set to 160 kHz.

Example 10

FIGS. 25A and 25B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 10 illustrated in the figure isone example of a standing wave in the case where 36 ejection holes 19are formed in a liquid column resonance-generating liquid chamber 11 ona fixed end side thereof, and thus the toner ejection holes 19 areformed to an extent of about one-third of the length of the liquidcolumn resonance-generating liquid chamber 11. In Example 10, whereas astanding wave in a resonance mode of N=2 was formed, this liquid dropletejection head had a loosely fixed end. Note that the drive frequency wasset to 468 kHz.

Example 11

FIGS. 26A and 26B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 11 illustrated in the figure isone example of a standing wave in the case where the liquid dropletejection head includes a liquid resonance flow path and an aperturepattern of ejection holes each having the same configuration as inExample 10, and the frequency was set to be slightly low. Note that thedrive frequency was set to 395 kHz. In a pattern of a resonance standingwave in this case, a pressure distribution is, as illustrated in FIG.28A, further equalized at a region where the toner ejection holes areclosely arranged. As compared with Example 10, a ratio of D4/DN becamesmall, i.e., the particle size distribution was further equalized. Asillustrated, even when the resonance patterns have the sameconfiguration, the particle distribution can be optimized byappropriately determining the drive frequency in a region where aresonance is generated.

Example 12

FIGS. 27A and 27B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 12 illustrated in the figure isone example of a standing wave in the case where four ejection holes arearranged on each of the fixed end side and the liquid common feed pathside. As just in the case of Example 5, a standing wave in a resonancemode of N=2 was formed. With this arrangement of the toner ejectionholes, the liquid could be ejected, in a uniform amount, from all thetoner ejection holes. Note that the drive frequency was set to 344 kHz.

Example 13

FIGS. 28A and 28B are diagrams illustrating still yet another example ofa liquid droplet ejection head. In Example 13 illustrated in the figure,the cross-sectional area of a liquid common feed path is greater thanthat of a liquid column resonance-generating liquid chamber, and theliquid droplet ejection head has, on the liquid common feed path side,an open end. In this case, a standing wave in a resonance mode of N=2was formed. Note that the drive frequency was set to 261 kHz.

Example 14

FIGS. 29A and 29B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 14 illustrated in the figure isan example when the liquid droplet ejection head has the sameconfiguration as in Example 13, however, the drive frequency is changed.The drive frequency was set to 516 kHz. In the case of Example 14, astanding wave in a resonance mode of N=4 was formed.

Example 15

FIGS. 20A and 20B are diagrams illustrating an example of a liquiddroplet ejection head. In FIG. 20A, as illustrated in Example 15,Example 15 is one example of a standing wave in the case where twoejection holes 19 are formed in a liquid column resonance-generatingliquid chamber 18 on a fixed end side thereof, and a reflection wall isprovided on the side of a liquid feed path in the liquid columnresonance-generating liquid chamber 18. It can be considered that thestanding wave is in a resonance mode of N=2 at both ends thereof. Notethat the drive frequency was set to 328 kHz. Example 15 illustrates theresult of driving using a frequency with a peaked resonance (resonancepeak). The term “resonance peak” is a node of a speed resonance standingwave in a resonance state, and an antinode of driving at a resonancepeak frequency, i.e., a state in which the pressure is in the highestcondition, liquid droplets are experimentally ejected, and it can bedetermined as a frequency at which the speed of ejection is the maximum,as illustrated in FIG. 17.

—Preparation of Colorant Dispersion Liquid—

First, a carbon black dispersion liquid was prepared as a colorant. Acarbon black (REGAL 400, produced by Cabot Corp.) (17 parts by mass), apigment dispersant (3 parts by mass), and ethyl acetate (80 parts bymass) were subjected to a primary dispersion by using a mixer having amixing blade. AJISPER PB821, produced by Ajinomoto Fine-Techno Co.,Inc., was used as the pigment dispersant. A dyno mill was employed tofinely disperse, by way of a powerful shearing force, the primarydispersion liquid, and a secondary dispersion liquid was prepared, inwhich aggregates of 5 μm or greater in size were completely removed.

—Preparation of Wax Dispersion Liquid—

Next, a wax dispersion liquid was prepared. A carnauba wax (18 parts bymass), a wax dispersant (2 parts by mass), and ethyl acetate (80 partsby mass) were subjected to a primary dispersal by using a mixer having amixing blade. The primary dispersion liquid was heated to 80° C. whilebeing mixed, thereby melting the carnauba wax, whereupon the temperatureof the solution was lowered to room temperature, and a wax particle wasprecipitated therefrom such that a maximum diameter of the wax particlewas 3 μm or smaller. As the wax dispersant, a substance was used whereina styrene-butyl acrylate copolymer was grafted upon a polyethylene wax.A dyno mill was employed to further finely disperse, by way of apowerful shearing force, the dispersion liquid, thereby adjusting suchthat a maximum diameter of the wax particle was 1 μm or smaller.

—Preparation of Toner Composition Dispersion Liquid—

Next, a toner composition dispersion liquid was prepared, which wasformed from a composition to be described hereinafter, wherein thebinder resin serving as a resin, the colorant dispersion liquid, and thewax dispersion liquid were added. The mixer having a mixing blade wasused for mixing for 10 minutes of a polyester resin (produced by DICCorp.) (100 parts by mass) as the binder resin, the colorant dispersionliquid (30 parts by mass), the wax dispersion liquid (30 parts by mass),and ethyl acetate (840 parts by mass), and uniformly dispersed. Neitherthe pigment nor the wax particles were aggregated by way of a dilutionof the solvent.

—Production of Toner—

The resulting toner composition liquid was stored in a toner productionapparatus illustrated in FIG. 13, which had having the above-mentionedliquid ejection head illustrated in FIG. 14. An air stream was caused togenerate in the same direction as the direction to which liquid dropletsproceed, by an air stream path 12. After preparation of a dispersionliquid, liquid droplets were ejected under the following conditions,followed by drying and solidifying the liquid droplets, to therebyproduce toner base particles.

[Conditions for Producing Toner]

Specific gravity of dispersion liquid: ρ=1.1888 [g/cm³]

Flow rate of dry air: 30.0 L/min

Inside temperature of device: 27° C. to 28° C.

Drive frequency: 328 kHz

Peak value of voltage sine wave applied: 10.0 V

The diameter of liquid droplets formed was 11.8 μm.

The toner particles that had been solidified by drying were subjected toa soft X-ray irradiation to eliminate electric charge therefrom and thencollected by suction through a filter having fine pores of 1 μm. Whenthe particle density distribution of the collected particles wasmeasured under a measuring condition that was mentioned hereinafter by aflow particle imaging analyzer, i.e., an FPIA-2000, the toner baseparticles were found to have a weight average particle diameter, i.e.,D4, of 5.5 μm, and a number average particle diameter, i.e., Dn, of 5.2μm, and a D4/Dn ratio of 1.06.

Following is a description relating to a measurement method that usesthe flow particle image analyzer. As an instance of a measurement of thetoner, the toner particle, and the external application agent, by way ofthe flow particle image analyzer, FPIA-2000 flow particle imageanalyzer, manufactured by TOA MEDICAL ELECTRONICS, INC. can be used.

The measurement applied a filter to remove particulate debris, and as aresult, a quantity of droplets of a nonionic surfactant, preferablyCONTAMINON N, manufactured by Wako Pure Chemical Industries Co., Ltd.,was added to 10 mL of water wherein the quantity of particles was lessthan or equal to 20 particles (equivalent circle diameter: greater thanor equal to 0.60 μm and less than 159.21 μm, for example), within ameasurement range in 10⁻³ cm³ of water. Furthermore, a measurementsample (5 mg) was added to the solution, a dispersion treatment wasperformed for one minute, using a UH-50 ultrasound dispersal device,manufactured by STM, under a condition of 20 kHz, and 50 W/cm³, andfurthermore, the dispersion treatment was performed for a total of 5minutes, thereafter a sample dispersion liquid was employed, having aparticle density of from 4,000 particles/10⁻³ cm³ to 8,000particles/10⁻³ cm³, (a particle corresponding to a range of anapproximate circle equivalent diameter of the assessment was targeted),and the particle density distribution of the particle having anapproximate circle equivalent diameter greater than or equal to 0.60 μmand less than 159.21 μm was measured.

The measurement sample dispersion liquid was passed through a flow path,which expanded in a direction of a flow of the toner, and which includeda flat, compressed, transparent flow cell, (thickness: about 200 μm). Inorder to form a light path that intersects and passed through thethickness of the flow cell, a strobe and a CCD camera was installed soas to be located on respectively opposite sides with respect to the flowcell. While the sample dispersion liquid flowing, the strobe light wasprojected at 1/30 second intervals, in order to obtain an image of theparticle that flows through the flow cell, and as a result, eachrespective particle thereupon was photographed as a two-dimensionalimage having a parallel fixed range within the flow cell. The diameterof the circle having a same surface area as the approximate circleequivalent diameter was computed, from a surface area of the twodimensional image of each respective particle thereupon.

It would be possible to measure the approximate circle equivalentdiameter of 1,200 or more particles within approximately one minute, andit would be possible to measure a proportion, i.e., a quantity as apercentage, of the particles that have the approximate circle equivalentdiameter that is quantified and regulated by a distribution of theapproximate circle equivalent diameter. It is possible to obtain aresult, i.e., a frequency percentage and a cumulative percentage, asshown in Table 1, wherein the range between 0.06 μm and 400 μm isdivided into 226 channels, such that one octave is divided into 30channels. With regard to an actual measurement, the measurement of theparticles is performed with the range of the approximate circleequivalent diameter being greater than or equal to 0.60 μm and less than159.21 μm.

(External Treatment)

After the toner base particles that had been dried and solidified andthen collected by a cyclone, a hydrophobized silica (H2000, produced byClariant Japan K.K.) (1.0% by mass) was externally added thereto, usinga HENSCHEL MIXER (manufactured by Mitsui Mining Co., to thereby producea toner.

(Preparation of Carrier)

A silicone resin (SR2406, produced by TORAY Dow Corning Silicone Co.,Ltd.) serving as a material for a coating layer was dispersed in tolueneto prepare a coating layer dispersion liquid, and then a core material(ferrite particles having average particle diameter of 50 μm) wasspray-coated with the coating layer dispersion liquid, baked, and cooledto thereby produce a carrier with the coating layer of 0.2 μm inthickness.

—Production of Developer—

The carrier (96 parts by mass) was mixed with the resulting toner (4parts by mass) to produce a two-component developer.

<Thin Line Reproducibility>

The developer was loaded into a modified version of a commerciallyavailable copier, i.e., an IMAGIO NEO 271, manufactured by Ricoh CompanyLtd., a development device portion whereof having been modified, and arun performed thereupon employing Ricoh 6000 Paper with an imageoccupied rate of 7%. A fine line portion of a 10th image at an initialstage of the run, and of a 30,000th image thereof, was compared with asource document, which were examined at 100× magnification under anoptical microscope, and evaluated at four grades, A, B, C and D by for astate of a line not being properly copied, in comparison with a samplein stages. The image quality is denoted from best to worst as follows:“A.>B>C>D” wherein the grade “D” denotes a level of imagereproducibility that is unusable as a viable product.

The line reproducibility evaluation results of Examples 16 to 27(Examples subsequent to Example 15) are also shown in Table 1.

TABLE 1 The number Drive Number Thin line of ejection frequency averageparticle reduc- holes (kHz) diameter (μm) D4/DN ibility Ex. 15 2 328 5.21.06 A Ex. 16 10 377 5.2 1.05 A Ex. 17 24 417 4.3 1.06 B Ex. 18 4 3444.9 1.04 A Ex. 19 23 160 5.8 1.09 B Ex. 20 24 468 5.2 1.12 B Ex. 21 24395 5.2 1.01 A Ex. 22 8 344 5.0 1.03 A Ex. 23 24 261 5.3 1.08 B Ex. 2424 516 3.9 1.09 A Ex. 25 2 328 4.6 1.05 A Ex. 26 2 238 4.8 1.09 A Ex. 272 328 4.4 1.05 A

Example 16

FIGS. 22A and 22B are diagrams illustrating another example of a liquiddroplet ejection head. Example 16 illustrated in the figure is oneexample of a standing wave in the case where ten ejection holes 19 areformed in a liquid column resonance-generating liquid chamber 18 on afixed end side thereof, and a reflection wall is provided on the side ofa liquid common feed path in the liquid column resonance-generatingliquid chamber 18. Note that the drive frequency was set to 377 kHz.Therefore, as compared with Example 15 illustrated in FIG. 20, thisliquid droplet ejection head was configured to have a loosely fixed end.

Example 17

FIGS. 22A and 22B are diagrams illustrating still another example of aliquid droplet ejection head. Example 17 illustrated in the figure isone example of a standing wave in the case where 24 ejection holes 19are formed in a liquid column resonance-generating liquid chamber 18 ona fixed end side thereof, and a reflection wall is provided on the sideof a liquid common feed path in the liquid column resonance-generatingliquid chamber 18. Note that the drive frequency was set to 417 kHz.Therefore, as compared with Example 15 illustrated in FIG. 20, theleading end side which was regarded as a fixed end in the liquid columnresonance-generating liquid chamber 18, a standing wave in a resonancemode of N=3, which is close to a standing wave formed at an open end,was formed.

Example 18

FIGS. 23A and 23B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 18 illustrated in the figure isone example of a standing wave in the case where four ejection holes 19are formed in a liquid column resonance-generating liquid chamber 18 ona fixed end side thereof, and a reflection wall is provided on the sideof a liquid common feed path in the liquid column resonance-generatingliquid chamber 18. Note that the drive frequency was set to 344 kHz.Therefore, as compared with Example 15 illustrated in FIG. 20, thisliquid droplet ejection head had a relatively loosely fixed end underthe influence of apertures of the ejection holes, in which a standingwave in a resonance mode of N=2 was formed.

Example 19

FIGS. 24A and 24B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 19 illustrated in the figure isone example of a standing wave in the case where the numerical apertureof toner ejection holes 19 is locally increased, the ejection holes 19are present near the liquid common feed path side and has a closed endat the other side of the liquid droplet ejection head. Thus, a standingwave in a resonance mode of N=1, which is a standing wave formed withclosed both ends, was formed, and as compared to a pressure distributionin a region provided with the toner ejection holes arranged near theliquid common feed path side, a pressure distribution in a regionprovided with the toner ejection holes arranged near the fixed end sidewas formed flat. Note that the drive frequency was set to 160 kHz.

Example 20

FIGS. 25A and 25B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 20 illustrated in the figure isone example of a standing wave in the case where 36 ejection holes 19are formed in a liquid column resonance-generating liquid chamber 18 ona fixed end side thereof, and thus the toner ejection holes 19 areformed to an extent of about one-third of the length of the liquidcolumn resonance-generating liquid chamber 18. In Example 20, whereas astanding wave in a resonance mode of N=2 was formed, this liquid dropletejection head had a loosely fixed end. Note that the drive frequency wasset to 468 kHz.

Example 21

FIGS. 26A and 26B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 21 illustrated in the figure isone example of a standing wave in the case where the liquid dropletejection head includes a liquid resonance flow path and an aperturepattern of ejection holes each having the same configuration as inExample 20, and the frequency was set to be slightly low. Note that thedrive frequency was set to 395 kHz. In a pattern of a resonance standingwave in this case, a pressure distribution is, as illustrated in FIG.28A, further equalized at a region where the toner ejection holes areclosely arranged. As compared with Example 20, a ratio of D4/DN becamesmall, i.e., the particle size distribution was further equalized. Asillustrated, even when the resonance patterns have the sameconfiguration, the particle distribution can be optimized byappropriately determining the drive frequency in a region where aresonance is generated.

Example 22

FIGS. 27A and 27B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 22 illustrated in the figure isone example of a standing wave in the case where four toner ejectionholes are arranged on each of the fixed end side and the liquid commonfeed path side. As just in the case of Example 15, a standing wave in aresonance mode of N=2 was formed. With this arrangement of the tonerejection holes, the liquid could be ejected, in a uniform amount, fromall the toner ejection holes. Note that the drive frequency was set to344 kHz.

Example 23

FIGS. 28A and 28B are diagrams illustrating still yet another example ofa liquid droplet ejection head. In Example 23 illustrated in the figure,the cross-sectional area of a liquid common feed path is greater thanthat of a liquid column resonance-generating liquid chamber, and theliquid droplet ejection head has, on the liquid common feed path side,an open end. In this case, a standing wave in a resonance mode of N=1was formed. Note that the drive frequency was set to 261 kHz.

Example 24

FIGS. 29A and 29B are diagrams illustrating still yet another example ofa liquid droplet ejection head. Example 24 illustrated in the figure isan example when the liquid droplet ejection head has the sameconfiguration as in Example 23, however, the drive frequency is changed.The drive frequency was set to 516 kHz. In the case of Example 24, astanding wave in a resonance mode of N=4 was formed.

Example 25

FIGS. 30A to 30E are diagrams illustrating still yet another example ofa liquid droplet ejection head. The liquid droplet ejection head ofExample 25 illustrated in the figure is an example where an air streampath 12, through which an air generated by an air stream generation unitdescribed in Example 15 is passed, has a different configuration. Thedirection of the air stream path 12, i.e., the direction to which airstream is passed, in Example 15 is the same as the direction to whichthe liquid droplets are ejected, however, the air stream path 12 inExample 25 includes a first air flow path 12-1 and a second air flowpath 12-2 which is formed in communicate with the first air flow path12-1 and connected to a vapor phase in a chamber 31 in a dry-collectionunit 30. The direction of the first air flow path 12-1 is a directionwhich is substantially orthogonal to the direction to which liquiddroplets are ejected, and the direction of the second air flow path 12-2is a direction which is substantially orthogonal to the direction of thefirst air flow path 12-1 and the same direction as the direction towhich liquid droplets are ejected. Note that the air flow rate was 20m/s at a region near the toner ejection holes; the number averageparticle diameter was 4.6 μm, and D4/DN was 1.05.

Example 26

FIG. 31 is a diagram illustrating still yet another example of a liquiddroplet ejection head. The liquid droplet ejection head of Example 26illustrated in the figure is an example where an air stream path 12,through which an air generated by an air stream generation unitdescribed in Example 15 is passed, has a different configuration. Thedirection of the air stream path 12, i.e., the direction to which airstream is passed, in Example 15 is the same as the direction to whichthe liquid droplets are ejected, however, the direction of the airstream path 12 in Example 26 is a direction substantially orthogonal tothe direction to which liquid droplets are ejected, and is the samedirection as the air stream flows in the vapor phase I a chamber 31 in adry-collection unit 30. Note that the air flow rate was 20 m/s at aregion near the toner ejection holes; the number average particlediameter was 4.8 and D4/DN was 1.09.

Example 27

Whereas the air stream in Example 26, illustrated in FIG. 31 was an airstream generated by pressure application by an air stream generatingunit, the air stream in Example 27 was an air stream generated bysuction forth, using an sucking unit disposed, for example, on the sideof the dry-collection unit 30. As for the configurations other thandescribed above, Example 27 has the same as in Example 26. Note that theair flow rate was 16 m/s at a region near the toner ejection holes; thenumber average particle diameter was 4.8 μm, and D4/DN was 1.09.

REFERENCE SIGNS LIST

-   -   1: toner production apparatus    -   10: liquid droplet ejection apparatus (Liquid droplet forming        unit)    -   11: liquid droplet ejection head    -   12: air stream path    -   12-1: first air flow path    -   12-2: second air flow path    -   13: material housing container    -   14: toner composition liquid    -   15: liquid circulation pump    -   16: liquid feed path    -   17: liquid common feed path    -   18: liquid column resonance-generating liquid chamber    -   19: ejection hole    -   20: vibration generating unit    -   21: liquid droplets    -   22: liquid return pipe    -   30: dry-collection unit    -   31: chamber    -   32: toner collection part    -   33: downward air stream    -   34: toner collection tube    -   35: toner reservoir part    -   100: inkjet recording apparatus    -   104: recording head

1. A liquid droplet ejecting method, the method comprising: applying avibration to a liquid in a liquid column resonance-generating liquidchamber, in which an ejection hole is formed, to form a standing wavethrough liquid column resonance; and ejecting the liquid from theejection hole, which is formed in a region corresponding to an antinodeof the standing wave, to form liquid droplets.
 2. The liquid dropletejecting method according to claim 1, wherein the ejection hole isformed in plurality with respect to at least one region corresponding tothe antinode.
 3. The liquid droplet ejecting method according to claim1, wherein the ejection hole is formed in plurality for each of theliquid column resonance-generating liquid chambers.
 4. The liquiddroplet ejecting method according to claim 1, wherein at least part ofboth ends of the liquid column resonance-generating liquid chamber in alongitudinal direction thereof is provided with a reflection wallsurface.
 5. The liquid droplet ejecting method according to claim 1,wherein the vibration is a high frequency vibration having a frequencyof 300 kHz or higher.
 6. The liquid droplet ejecting method according toclaim 1, wherein a drive signal from a vibration generating unit excitesthe vibration generating unit by pulse groups which is primarilycomposed of a liquid column resonance frequency depending on the lengthof the liquid column resonance-generating liquid chamber in thelongitudinal direction thereof.
 7. The liquid droplet ejecting methodaccording to claim 6, wherein: the pulse groups are divided into threepulse parts of a preparatory pressure generating pulse part, a drivemain pulse part, and a residual vibration undoing pulse part; thepreparatory pressure generating pulse part is present at a leading edgeof the pulse groups and excites the liquid in the liquid columnresonance-generating liquid chamber to allow the liquid to remain in astate of not flying the liquid droplets; the drive main pulse part is anapplication pulse which follows the preparatory generating pulse partand ejects the liquid from the ejection hole; and the residual vibrationundoing pulse part is an application pulse immediately after the drivemain pulse part and includes a frequency component having a phaseopposite to that of a main frequency component of the drive main pulsepart.
 8. A liquid droplet ejection apparatus comprising: a liquid columnresonance-generating liquid chamber in a part of which an ejection holeis formed; and a vibration generating unit configured to apply avibration to a liquid, wherein the vibration is applied to the liquid inthe liquid column resonance-generating liquid chamber by the vibrationgenerating unit to form a standing wave through liquid column resonance,and the liquid is ejected from the ejection hole corresponding to anantinode of the standing wave.
 9. An inkjet recording apparatus, whichejects a liquid from at least one ejection hole to form the liquid intoliquid droplet by the method of claim
 1. 10. The liquid droplet ejectingmethod of claim 1, which is suitable for ejecting a liquid from at leastone ejection hole to form the liquid into liquid droplets.
 11. Theliquid droplet ejection apparatus of claim 8, which is suitable forejecting a liquid from at least one ejection hole to form the liquidinto liquid droplets.
 12. An inkjet recording apparatus, comprising theliquid droplet apparatus of claim 8.